[cssom] Make CSSOM APIs always append to the declaration block.

...instead of replacing if the property is already set.

This matches the spec[1] which was changed as a resolution from[2].

Intent thread: https://groups.google.com/a/chromium.org/d/msg/blink-dev/lzBoa1EAQpI/strfpNczAwAJ

[1]: https://drafts.csswg.org/cssom/#set-a-css-declaration
[2]: https://github.com/w3c/csswg-drafts/issues/1898

Bug: 782407
Change-Id: I4b72c0207a4cf734fc2e415bd62c7863103ec309
Reviewed-on: https://chromium-review.googlesource.com/1054867
Commit-Queue: Emilio Cobos Álvarez <emilio@chromium.org>
Reviewed-by: Rune Lillesveen <futhark@chromium.org>
Cr-Commit-Position: refs/heads/master@{#560180}

third_party/WebKit/LayoutTests/TestExpectations

@@ -2934,7 +2934,6 @@ crbug.com/626703 external/wpt/mediacapture-streams/MediaStream-MediaElement-prel
 crbug.com/626703 virtual/feature-policy-permissions/external/wpt/mediacapture-streams/MediaStream-MediaElement-preload-none-manual.https.html [ Skip ]
 crbug.com/626703 external/wpt/css/vendor-imports/mozilla/mozilla-central-reftests/flexbox/flexbox-flex-basis-content-003a.html [ Failure ]
 crbug.com/626703 external/wpt/css/vendor-imports/mozilla/mozilla-central-reftests/flexbox/flexbox-flex-basis-content-004a.html [ Failure ]
-crbug.com/626703 external/wpt/css/cssom/cssstyledeclaration-mutationrecord-001.html [ Timeout ]
 crbug.com/626703 external/wpt/css/css-shapes/shape-outside/shape-image/gradients/shape-outside-linear-gradient-008.html [ Failure ]
 crbug.com/626703 [ Mac10.11 ] virtual/webrtc-wpt-unified-plan/external/wpt/webrtc/RTCPeerConnection-track-stats.https.html [ Timeout ]
 crbug.com/626703 external/wpt/css/css-shapes/shape-outside/shape-image/gradients/shape-outside-linear-gradient-006.html [ Failure ]
@@ -4386,9 +4385,6 @@ crbug.com/778745 http/tests/inspector-protocol/cachestorage/read-cached-response
 # Sheriff failures 2017-10-24
 crbug.com/773122 crbug.com/777813 [ Win ] fast/text/font-ascent-mac.html [ Failure Pass ]
 
-# Sheriff failures 2017-11-07
-crbug.com/782067 [ Mac10.10 Mac10.11 ] fast/css/no-recalc-on-no-op-inline-style-changes.html [ Pass Failure ]
-
 # Sheriff failures 2017-11-13
 crbug.com/783800 imagecapture/MediaStreamTrack-applyConstraints.html [ Pass Failure ]
 crbug.com/783800 imagecapture/MediaStreamTrack-applyConstraints-getSettings.html [ Pass Failure ]

third_party/WebKit/LayoutTests/editing/pasteboard/dragstart-contains-default-content-expected.txt

@@ -9,7 +9,7 @@ Drag the link. Link
 Test ID: selectionTest
 text/plain: Select some text in this box and drag it.
 text/url: 
-text/html: <span style="color: rgb(0, 0, 0); font-family: serif; font-size: medium; font-style: normal; font-variant-ligatures: normal; font-variant-caps: normal; font-weight: 400; letter-spacing: normal; orphans: 2; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; widows: 2; word-spacing: 0px; -webkit-text-stroke-width: 0px; text-decoration-style: initial; text-decoration-color: initial; display: inline !important; float: none;">Select some text in this box and drag it.</span>
+text/html: <span style="color: rgb(0, 0, 0); font-family: serif; font-style: normal; font-variant-ligatures: normal; font-variant-caps: normal; font-weight: 400; letter-spacing: normal; orphans: 2; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; widows: 2; word-spacing: 0px; -webkit-text-stroke-width: 0px; text-decoration-style: initial; text-decoration-color: initial; font-size: medium; display: inline !important; float: none;">Select some text in this box and drag it.</span>
 Test ID: imageTest
 text/plain: 
 text/url: 

third_party/WebKit/LayoutTests/editing/pasteboard/onpaste-text-html-expected.txt

 CONSOLE MESSAGE: line 21: text/plain: This test verifies that we can get text/html from the clipboard during an onpaste event. 
-CONSOLE MESSAGE: line 23: text/html: <span style="color: rgb(0, 0, 0); font-size: medium; font-style: normal; font-variant-ligatures: normal; font-variant-caps: normal; font-weight: 400; letter-spacing: normal; orphans: 2; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; widows: 2; word-spacing: 0px; -webkit-text-stroke-width: 0px; text-decoration-style: initial; text-decoration-color: initial; display: inline !important; float: none;">This test verifies that we can get text/html from the clipboard during an onpaste event.<span> </span></span>
+CONSOLE MESSAGE: line 23: text/html: <span style="color: rgb(0, 0, 0); font-style: normal; font-variant-ligatures: normal; font-variant-caps: normal; font-weight: 400; letter-spacing: normal; orphans: 2; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; widows: 2; word-spacing: 0px; -webkit-text-stroke-width: 0px; text-decoration-style: initial; text-decoration-color: initial; font-size: medium; display: inline !important; float: none;">This test verifies that we can get text/html from the clipboard during an onpaste event.<span> </span></span>
 This test verifies that we can get text/html from the clipboard during an onpaste event. This test requires DRT.
 Paste content in this div.This test verifies that we can get text/html from the clipboard during an onpaste event. 
 PASS

third_party/WebKit/LayoutTests/external/wpt/css/cssom/cssstyledeclaration-setter-order-expected.txt

-This is a testharness.js-based test.
-FAIL setProperty with existing longhand should change order assert_array_equals: Property order should match after setting existing property property 0, expected "bottom" but got "top"
-FAIL invoke property setter with existing longhand should change order assert_array_equals: Property order should match after setting existing property property 0, expected "bottom" but got "top"
-FAIL setProperty with existing shorthand should change order assert_array_equals: Property order should match after setting an existing shorthand property 0, expected "top" but got "margin-top"
-FAIL invoke property setter with existing shorthand should change order assert_array_equals: Property order should match after setting an existing shorthand property 0, expected "top" but got "margin-top"
-Harness: the test ran to completion.
-

third_party/WebKit/LayoutTests/fast/css/no-recalc-on-no-op-inline-style-changes.html

-<!DOCTYPE html>
-<div id="element"></div>
-
-<script src="../../resources/testharness.js"></script>
-<script src="../../resources/testharnessreport.js"></script>
-<script>
-test(function () {
-  if (!window.internals)
-    assert_unreached('This test requires window.internals.');
-
-  assert_greater_than(internals.updateStyleAndReturnAffectedElementCount(), 1);
-
-  element.style.top = "0px";
-  assert_equals(internals.updateStyleAndReturnAffectedElementCount(), 1);
-
-  for (var i = 0; i < 100; i ++) {
-    element.style.top = "0px";
-    assert_equals(internals.updateStyleAndReturnAffectedElementCount(), 0);
-  }
-}, "Check that a no-op inline style change doesn't result in a recalc");
-</script>

third_party/WebKit/LayoutTests/fast/dom/MutationObserver/observe-attributes-expected.txt

@@ -173,7 +173,7 @@ PASS mutations[0].attributeName is "style"
 PASS mutations[0].oldValue is "color: yellow; width: 100px;"
 PASS mutations[1].type is "attributes"
 PASS mutations[1].attributeName is "style"
-PASS mutations[1].oldValue is "color: red; width: 100px;"
+PASS mutations[1].oldValue is "width: 100px; color: red;"
 PASS mutations[2].type is "attributes"
 PASS mutations[2].attributeName is "style"
 PASS mutations[2].oldValue is "color: red; width: 200px;"

third_party/WebKit/LayoutTests/fast/dom/MutationObserver/observe-attributes.html

@@ -715,7 +715,7 @@ function testStyleAttributePropertyAccessOldValue() {
         shouldBe('mutations[0].oldValue', '"color: yellow; width: 100px;"');
         shouldBe('mutations[1].type', '"attributes"');
         shouldBe('mutations[1].attributeName', '"style"');
-        shouldBe('mutations[1].oldValue', '"color: red; width: 100px;"');
+        shouldBe('mutations[1].oldValue', '"width: 100px; color: red;"');
         shouldBe('mutations[2].type', '"attributes"');
         shouldBe('mutations[2].attributeName', '"style"');
         shouldBe('mutations[2].oldValue', '"color: red; width: 200px;"');

third_party/WebKit/LayoutTests/fast/dom/css-set-property-exception-expected.txt

@@ -6,11 +6,11 @@ It is OK if the order of properties changes from the expected results - IE 6 and
 
 This is the test element.
 
-Successfully set display to "block"; cssText is now: "top: 0px; display: block; bottom: 1px;".
+Successfully set display to "block"; cssText is now: "top: 0px; bottom: 1px; display: block;".
 Successfully set display to "foobar"; cssText is now: "top: 0px; display: none; bottom: 1px;".
 Successfully set display to ""; cssText is now: "top: 0px; bottom: 1px;".
 Successfully set display to null; cssText is now: "top: 0px; bottom: 1px;".
-Successfully set display to "block" with setProperty; cssText is now: "top: 0px; display: block; bottom: 1px;".
+Successfully set display to "block" with setProperty; cssText is now: "top: 0px; bottom: 1px; display: block;".
 Successfully set display to "foobar" with setProperty; cssText is now: "top: 0px; display: none; bottom: 1px;".
 Successfully set display to "" with setProperty; cssText is now: "top: 0px; bottom: 1px;".
 Successfully set display to null with setProperty; cssText is now: "top: 0px; bottom: 1px;".

third_party/WebKit/LayoutTests/fast/events/ondrop-text-html-expected.txt

 CONSOLE MESSAGE: line 21: text/plain: This test verifies that we can get text/html from the drag object during an ondrop event. 
-CONSOLE MESSAGE: line 23: text/html: <span style="color: rgb(0, 0, 0); font-size: medium; font-style: normal; font-variant-ligatures: normal; font-variant-caps: normal; font-weight: 400; letter-spacing: normal; orphans: 2; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; widows: 2; word-spacing: 0px; -webkit-text-stroke-width: 0px; text-decoration-style: initial; text-decoration-color: initial; display: inline !important; float: none;">This test verifies that we can get text/html from the drag object during an ondrop event.<span> </span></span>
+CONSOLE MESSAGE: line 23: text/html: <span style="color: rgb(0, 0, 0); font-style: normal; font-variant-ligatures: normal; font-variant-caps: normal; font-weight: 400; letter-spacing: normal; orphans: 2; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; widows: 2; word-spacing: 0px; -webkit-text-stroke-width: 0px; text-decoration-style: initial; text-decoration-color: initial; font-size: medium; display: inline !important; float: none;">This test verifies that we can get text/html from the drag object during an ondrop event.<span> </span></span>
 This test verifies that we can get text/html from the drag object during an ondrop event. This test requires DRT.
 PASS

third_party/blink/renderer/core/css/css_property_value_set.cc

@@ -360,10 +360,11 @@ MutableCSSPropertyValueSet::SetResult MutableCSSPropertyValueSet::SetProperty(
   }
 
   // When replacing an existing property value, this moves the property to the
-  // end of the list. Firefox preserves the position, and MSIE moves the
-  // property to the beginning.
-  return CSSParser::ParseValue(this, unresolved_property, value, important,
-                               secure_context_mode, context_style_sheet);
+  // end of the list.
+  bool parsed_and_changed =
+      CSSParser::ParseValue(this, unresolved_property, value, important,
+                            secure_context_mode, context_style_sheet);
+  return SetResult{parsed_and_changed, parsed_and_changed};
 }
 
 MutableCSSPropertyValueSet::SetResult MutableCSSPropertyValueSet::SetProperty(
@@ -377,11 +378,12 @@ MutableCSSPropertyValueSet::SetResult MutableCSSPropertyValueSet::SetProperty(
   if (value.IsEmpty()) {
     bool did_parse = true;
     bool did_change = RemoveProperty(custom_property_name);
-    return MutableCSSPropertyValueSet::SetResult{did_parse, did_change};
+    return SetResult{did_parse, did_change};
   }
-  return CSSParser::ParseValueForCustomProperty(
+  bool parsed_and_changed = CSSParser::ParseValueForCustomProperty(
       this, custom_property_name, registry, value, important,
       secure_context_mode, context_style_sheet, is_animation_tainted);
+  return SetResult{parsed_and_changed, parsed_and_changed};
 }
 
 void MutableCSSPropertyValueSet::SetProperty(CSSPropertyID property_id,
@@ -402,31 +404,22 @@ void MutableCSSPropertyValueSet::SetProperty(CSSPropertyID property_id,
   }
 }
 
-bool MutableCSSPropertyValueSet::SetProperty(const CSSPropertyValue& property,
+void MutableCSSPropertyValueSet::SetProperty(const CSSPropertyValue& property,
                                              CSSPropertyValue* slot) {
-  const AtomicString& name =
-      (property.Id() == CSSPropertyVariable)
-          ? ToCSSCustomPropertyDeclaration(property.Value())->GetName()
-          : g_null_atom;
-  CSSPropertyValue* to_replace =
-      slot ? slot : FindCSSPropertyWithID(property.Id(), name);
-  if (to_replace && *to_replace == property)
-    return false;
-  if (to_replace) {
-    *to_replace = property;
-    return true;
+  if (property.Id() == CSSPropertyVariable) {
+    RemoveProperty(ToCSSCustomPropertyDeclaration(property.Value())->GetName());
+  } else {
+    RemoveProperty(property.Id());
   }
   property_vector_.push_back(property);
-  return true;
 }
 
-bool MutableCSSPropertyValueSet::SetProperty(CSSPropertyID property_id,
+void MutableCSSPropertyValueSet::SetProperty(CSSPropertyID property_id,
                                              CSSValueID identifier,
                                              bool important) {
   SetProperty(CSSPropertyValue(CSSProperty::Get(property_id),
                                *CSSIdentifierValue::Create(identifier),
                                important));
-  return true;
 }
 
 void MutableCSSPropertyValueSet::ParseDeclarationList(
@@ -447,21 +440,20 @@ void MutableCSSPropertyValueSet::ParseDeclarationList(
   CSSParser::ParseDeclarationList(context, this, style_declaration);
 }
 
-bool MutableCSSPropertyValueSet::AddParsedProperties(
+void MutableCSSPropertyValueSet::AddParsedProperties(
     const HeapVector<CSSPropertyValue, 256>& properties) {
-  bool changed = false;
   property_vector_.ReserveCapacity(property_vector_.size() + properties.size());
   for (unsigned i = 0; i < properties.size(); ++i)
-    changed |= SetProperty(properties[i]);
-  return changed;
+    SetProperty(properties[i]);
 }
 
 bool MutableCSSPropertyValueSet::AddRespectingCascade(
     const CSSPropertyValue& property) {
   // Only add properties that have no !important counterpart present
-  if (!PropertyIsImportant(property.Id()) || property.IsImportant())
-    return SetProperty(property);
-  return false;
+  if (PropertyIsImportant(property.Id()) && !property.IsImportant())
+    return false;
+  SetProperty(property);
+  return true;
 }
 
 String CSSPropertyValueSet::AsText() const {

third_party/blink/renderer/core/css/css_property_value_set.h

@@ -227,7 +227,7 @@ class CORE_EXPORT MutableCSSPropertyValueSet : public CSSPropertyValueSet {
   unsigned PropertyCount() const { return property_vector_.size(); }
 
   // Returns whether this style set was changed.
-  bool AddParsedProperties(const HeapVector<CSSPropertyValue, 256>&);
+  void AddParsedProperties(const HeapVector<CSSPropertyValue, 256>&);
   bool AddRespectingCascade(const CSSPropertyValue&);
 
   struct SetResult {
@@ -250,10 +250,10 @@ class CORE_EXPORT MutableCSSPropertyValueSet : public CSSPropertyValueSet {
   void SetProperty(CSSPropertyID, const CSSValue&, bool important = false);
 
   // These do not. FIXME: This is too messy, we can do better.
-  bool SetProperty(CSSPropertyID,
+  void SetProperty(CSSPropertyID,
                    CSSValueID identifier,
                    bool important = false);
-  bool SetProperty(const CSSPropertyValue&, CSSPropertyValue* slot = nullptr);
+  void SetProperty(const CSSPropertyValue&, CSSPropertyValue* slot = nullptr);
 
   template <typename T>  // CSSPropertyID or AtomicString
   bool RemoveProperty(T property, String* return_text = nullptr);

third_party/blink/renderer/core/css/dom_window_css.cc

@@ -50,10 +50,9 @@ bool DOMWindowCSS::supports(const ExecutionContext* execution_context,
         MutableCSSPropertyValueSet::Create(kHTMLStandardMode);
     bool is_animation_tainted = false;
     return CSSParser::ParseValueForCustomProperty(
-               dummy_style, "--valid", nullptr, value, false,
-               execution_context->GetSecureContextMode(), nullptr,
-               is_animation_tainted)
-        .did_parse;
+        dummy_style, "--valid", nullptr, value, false,
+        execution_context->GetSecureContextMode(), nullptr,
+        is_animation_tainted);
   }
 
 #if DCHECK_IS_ON()
@@ -65,8 +64,7 @@ bool DOMWindowCSS::supports(const ExecutionContext* execution_context,
   MutableCSSPropertyValueSet* dummy_style =
       MutableCSSPropertyValueSet::Create(kHTMLStandardMode);
   return CSSParser::ParseValue(dummy_style, unresolved_property, value, false,
-                               execution_context->GetSecureContextMode())
-      .did_parse;
+                               execution_context->GetSecureContextMode());
 }
 
 bool DOMWindowCSS::supports(const ExecutionContext* execution_context,

third_party/blink/renderer/core/css/parser/css_parser.cc

@@ -81,28 +81,24 @@ void CSSParser::ParseSheetForInspector(const CSSParserContext* context,
                                                     observer);
 }
 
-MutableCSSPropertyValueSet::SetResult CSSParser::ParseValue(
-    MutableCSSPropertyValueSet* declaration,
-    CSSPropertyID unresolved_property,
-    const String& string,
-    bool important,
-    SecureContextMode secure_context_mode) {
+bool CSSParser::ParseValue(MutableCSSPropertyValueSet* declaration,
+                           CSSPropertyID unresolved_property,
+                           const String& string,
+                           bool important,
+                           SecureContextMode secure_context_mode) {
   return ParseValue(declaration, unresolved_property, string, important,
                     secure_context_mode,
                     static_cast<StyleSheetContents*>(nullptr));
 }
 
-MutableCSSPropertyValueSet::SetResult CSSParser::ParseValue(
-    MutableCSSPropertyValueSet* declaration,
-    CSSPropertyID unresolved_property,
-    const String& string,
-    bool important,
-    SecureContextMode secure_context_mode,
-    StyleSheetContents* style_sheet) {
+bool CSSParser::ParseValue(MutableCSSPropertyValueSet* declaration,
+                           CSSPropertyID unresolved_property,
+                           const String& string,
+                           bool important,
+                           SecureContextMode secure_context_mode,
+                           StyleSheetContents* style_sheet) {
   if (string.IsEmpty()) {
-    bool did_parse = false;
-    bool did_change = false;
-    return MutableCSSPropertyValueSet::SetResult{did_parse, did_change};
+    return false;
   }
 
   CSSPropertyID resolved_property = resolveCSSPropertyID(unresolved_property);
@@ -110,10 +106,9 @@ MutableCSSPropertyValueSet::SetResult CSSParser::ParseValue(
   CSSValue* value = CSSParserFastPaths::MaybeParseValue(resolved_property,
                                                         string, parser_mode);
   if (value) {
-    bool did_parse = true;
-    bool did_change = declaration->SetProperty(CSSPropertyValue(
+    declaration->SetProperty(CSSPropertyValue(
         CSSProperty::Get(resolved_property), *value, important));
-    return MutableCSSPropertyValueSet::SetResult{did_parse, did_change};
+    return true;
   }
   CSSParserContext* context;
   if (style_sheet) {
@@ -126,7 +121,7 @@ MutableCSSPropertyValueSet::SetResult CSSParser::ParseValue(
                     context);
 }
 
-MutableCSSPropertyValueSet::SetResult CSSParser::ParseValueForCustomProperty(
+bool CSSParser::ParseValueForCustomProperty(
     MutableCSSPropertyValueSet* declaration,
     const AtomicString& property_name,
     const PropertyRegistry* registry,
@@ -137,9 +132,7 @@ MutableCSSPropertyValueSet::SetResult CSSParser::ParseValueForCustomProperty(
     bool is_animation_tainted) {
   DCHECK(CSSVariableParser::IsValidVariableName(property_name));
   if (value.IsEmpty()) {
-    bool did_parse = false;
-    bool did_change = false;
-    return MutableCSSPropertyValueSet::SetResult{did_parse, did_change};
+    return false;
   }
   CSSParserMode parser_mode = declaration->CssParserMode();
   CSSParserContext* context;
@@ -154,12 +147,11 @@ MutableCSSPropertyValueSet::SetResult CSSParser::ParseValueForCustomProperty(
                                            is_animation_tainted);
 }
 
-MutableCSSPropertyValueSet::SetResult CSSParser::ParseValue(
-    MutableCSSPropertyValueSet* declaration,
-    CSSPropertyID unresolved_property,
-    const String& string,
-    bool important,
-    const CSSParserContext* context) {
+bool CSSParser::ParseValue(MutableCSSPropertyValueSet* declaration,
+                           CSSPropertyID unresolved_property,
+                           const String& string,
+                           bool important,
+                           const CSSParserContext* context) {
   return CSSParserImpl::ParseValue(declaration, unresolved_property, string,
                                    important, context);
 }

third_party/blink/renderer/core/css/parser/css_parser.h

@@ -47,29 +47,26 @@ class CORE_EXPORT CSSParser {
                                    MutableCSSPropertyValueSet*,
                                    const String&);
 
-  static MutableCSSPropertyValueSet::SetResult ParseValue(
-      MutableCSSPropertyValueSet*,
-      CSSPropertyID unresolved_property,
-      const String&,
-      bool important,
-      SecureContextMode);
-  static MutableCSSPropertyValueSet::SetResult ParseValue(
-      MutableCSSPropertyValueSet*,
-      CSSPropertyID unresolved_property,
-      const String&,
-      bool important,
-      SecureContextMode,
-      StyleSheetContents*);
-
-  static MutableCSSPropertyValueSet::SetResult ParseValueForCustomProperty(
-      MutableCSSPropertyValueSet*,
-      const AtomicString& property_name,
-      const PropertyRegistry*,
-      const String& value,
-      bool important,
-      SecureContextMode,
-      StyleSheetContents*,
-      bool is_animation_tainted);
+  static bool ParseValue(MutableCSSPropertyValueSet*,
+                         CSSPropertyID unresolved_property,
+                         const String&,
+                         bool important,
+                         SecureContextMode);
+  static bool ParseValue(MutableCSSPropertyValueSet*,
+                         CSSPropertyID unresolved_property,
+                         const String&,
+                         bool important,
+                         SecureContextMode,
+                         StyleSheetContents*);
+
+  static bool ParseValueForCustomProperty(MutableCSSPropertyValueSet*,
+                                          const AtomicString& property_name,
+                                          const PropertyRegistry*,
+                                          const String& value,
+                                          bool important,
+                                          SecureContextMode,
+                                          StyleSheetContents*,
+                                          bool is_animation_tainted);
 
   // This is for non-shorthands only
   static const CSSValue* ParseSingleValue(CSSPropertyID,
@@ -104,12 +101,11 @@ class CORE_EXPORT CSSParser {
                                                CSSParserObserver&);
 
  private:
-  static MutableCSSPropertyValueSet::SetResult ParseValue(
-      MutableCSSPropertyValueSet*,
-      CSSPropertyID unresolved_property,
-      const String&,
-      bool important,
-      const CSSParserContext*);
+  static bool ParseValue(MutableCSSPropertyValueSet*,
+                         CSSPropertyID unresolved_property,
+                         const String&,
+                         bool important,
+                         const CSSParserContext*);
 };
 
 }  // namespace blink

third_party/blink/renderer/core/css/parser/css_parser_impl.cc

@@ -65,12 +65,11 @@ CSSParserImpl::CSSParserImpl(const CSSParserContext* context,
                              StyleSheetContents* style_sheet)
     : context_(context), style_sheet_(style_sheet), observer_(nullptr) {}
 
-MutableCSSPropertyValueSet::SetResult CSSParserImpl::ParseValue(
-    MutableCSSPropertyValueSet* declaration,
-    CSSPropertyID unresolved_property,
-    const String& string,
-    bool important,
-    const CSSParserContext* context) {
+bool CSSParserImpl::ParseValue(MutableCSSPropertyValueSet* declaration,
+                               CSSPropertyID unresolved_property,
+                               const String& string,
+                               bool important,
+                               const CSSParserContext* context) {
   CSSParserImpl parser(context);
   StyleRule::RuleType rule_type = StyleRule::kStyle;
   if (declaration->CssParserMode() == kCSSViewportRuleMode)
@@ -81,23 +80,20 @@ MutableCSSPropertyValueSet::SetResult CSSParserImpl::ParseValue(
   // TODO(crbug.com/661854): Use streams instead of ranges
   parser.ConsumeDeclarationValue(CSSParserTokenRange(tokenizer.TokenizeToEOF()),
                                  unresolved_property, important, rule_type);
-  bool did_parse = false;
-  bool did_change = false;
-  if (!parser.parsed_properties_.IsEmpty()) {
-    did_parse = true;
-    did_change = declaration->AddParsedProperties(parser.parsed_properties_);
+  if (parser.parsed_properties_.IsEmpty()) {
+    return false;
   }
-  return MutableCSSPropertyValueSet::SetResult{did_parse, did_change};
+  declaration->AddParsedProperties(parser.parsed_properties_);
+  return true;
 }
 
-MutableCSSPropertyValueSet::SetResult CSSParserImpl::ParseVariableValue(
-    MutableCSSPropertyValueSet* declaration,
-    const AtomicString& property_name,
-    const PropertyRegistry* registry,
-    const String& value,
-    bool important,
-    const CSSParserContext* context,
-    bool is_animation_tainted) {
+bool CSSParserImpl::ParseVariableValue(MutableCSSPropertyValueSet* declaration,
+                                       const AtomicString& property_name,
+                                       const PropertyRegistry* registry,
+                                       const String& value,
+                                       bool important,
+                                       const CSSParserContext* context,
+                                       bool is_animation_tainted) {
   CSSParserImpl parser(context);
   CSSTokenizer tokenizer(value);
   // TODO(crbug.com/661854): Use streams instead of ranges
@@ -105,25 +101,23 @@ MutableCSSPropertyValueSet::SetResult CSSParserImpl::ParseVariableValue(
   const CSSParserTokenRange range(tokens);
   parser.ConsumeVariableValue(range, property_name, important,
                               is_animation_tainted);
-  bool did_parse = false;
-  bool did_change = false;
-  if (!parser.parsed_properties_.IsEmpty()) {
-    const CSSCustomPropertyDeclaration* parsed_declaration =
-        ToCSSCustomPropertyDeclaration(parser.parsed_properties_[0].Value());
-    if (parsed_declaration->Value() && registry) {
-      const PropertyRegistration* registration =
-          registry->Registration(property_name);
-      // TODO(timloh): This is a bit wasteful, we parse the registered property
-      // to validate but throw away the result.
-      if (registration &&
-          !registration->Syntax().Parse(range, context, is_animation_tainted)) {
-        return MutableCSSPropertyValueSet::SetResult{did_parse, did_change};
-      }
+  if (parser.parsed_properties_.IsEmpty())
+    return false;
+
+  const CSSCustomPropertyDeclaration* parsed_declaration =
+      ToCSSCustomPropertyDeclaration(parser.parsed_properties_[0].Value());
+  if (parsed_declaration->Value() && registry) {
+    const PropertyRegistration* registration =
+        registry->Registration(property_name);
+    // TODO(timloh): This is a bit wasteful, we parse the registered property
+    // to validate but throw away the result.
+    if (registration &&
+        !registration->Syntax().Parse(range, context, is_animation_tainted)) {
+      return false;
     }
-    did_parse = true;
-    did_change = declaration->AddParsedProperties(parser.parsed_properties_);
   }
-  return MutableCSSPropertyValueSet::SetResult{did_parse, did_change};
+  declaration->AddParsedProperties(parser.parsed_properties_);
+  return true;
 }
 
 static inline void FilterProperties(
@@ -216,7 +210,8 @@ bool CSSParserImpl::ParseDeclarationList(
                    seen_properties, seen_custom_properties);
   if (unused_entries)
     results.EraseAt(0, unused_entries);
-  return declaration->AddParsedProperties(results);
+  declaration->AddParsedProperties(results);
+  return true;
 }
 
 StyleRuleBase* CSSParserImpl::ParseRule(const String& string,

third_party/blink/renderer/core/css/parser/css_parser_impl.h

@@ -71,20 +71,18 @@ class CSSParserImpl {
     static RangeOffset Ignore() { return {0, 0}; }
   };
 
-  static MutableCSSPropertyValueSet::SetResult ParseValue(
-      MutableCSSPropertyValueSet*,
-      CSSPropertyID,
-      const String&,
-      bool important,
-      const CSSParserContext*);
-  static MutableCSSPropertyValueSet::SetResult ParseVariableValue(
-      MutableCSSPropertyValueSet*,
-      const AtomicString& property_name,
-      const PropertyRegistry*,
-      const String&,
-      bool important,
-      const CSSParserContext*,
-      bool is_animation_tainted);
+  static bool ParseValue(MutableCSSPropertyValueSet*,
+                         CSSPropertyID,
+                         const String&,
+                         bool important,
+                         const CSSParserContext*);
+  static bool ParseVariableValue(MutableCSSPropertyValueSet*,
+                                 const AtomicString& property_name,
+                                 const PropertyRegistry*,
+                                 const String&,
+                                 bool important,
+                                 const CSSParserContext*,
+                                 bool is_animation_tainted);
   static ImmutableCSSPropertyValueSet* ParseInlineStyleDeclaration(
       const String&,
       Element*);