Implement Document.createEmptyCSSStyleSheet

Currently, empty CSSStyleSheets can only be constructed using a constructor method.
This CL adds Document.createEmptyCSSStyleSheet so that it can be tied to document in the future.
Tying it to document restricts the use of a CSSStyleSheet in different documents, which means CSSStyleSheets can only be used in the documents where they are constructed. This will reduce security risk.

Note:
The constructed CSSStyleSheet is not currently tied to the Document yet
Constructor method will be deleted in another CL
createEmptyCSSStyleSheet(CSSStyleSheetInit) produces an empty CSSStyleSheet, while createCSSStyleSheet(text, CSSStyleSheetInit) creates a CSSStyleSheet with text

Link to related comments in discussion:
https://github.com/WICG/construct-stylesheets/issues/23#issuecomment-379180786
https://github.com/WICG/construct-stylesheets/issues/15#issuecomment-391216056

Bug: 807560

Change-Id: I94ea6f795deaf0dee67fba5c2705c8749ac72da8
Reviewed-on: https://chromium-review.googlesource.com/1160422
Commit-Queue: Momoko Sumida <momon@google.com>
Reviewed-by: Hayato Ito <hayato@chromium.org>
Reviewed-by: Rakina Zata Amni <rakina@chromium.org>
Cr-Commit-Position: refs/heads/master@{#581169}

third_party/WebKit/LayoutTests/fast/css/CSSStyleSheet-constructable.html

@@ -28,6 +28,56 @@ test(() => {
   assert_equals(sheet.cssRules[0].cssText, redStyleTexts[1]);
 }, 'Empty CSSStyleSheet can be constructed using script');
 
+test(() => {
+  const sheet = document.createEmptyCSSStyleSheet({title: "Red", disabled: true, media: "screen, print"});
+  assert_equals(sheet.title, "Red");
+  assert_equals(sheet.ownerNode, null);
+  assert_equals(sheet.ownerRule, null);
+  assert_equals(sheet.media.length, 2);
+  assert_equals(sheet.media.item(0), "screen");
+  assert_equals(sheet.media.item(1), "print");
+  assert_true(sheet.disabled);
+  assert_equals(sheet.cssRules.length, 0);
+
+  sheet.insertRule(redStyleTexts[0]);
+  assert_equals(sheet.cssRules.length, 1);
+  assert_equals(sheet.cssRules[0].cssText, redStyleTexts[0]);
+
+  sheet.insertRule(redStyleTexts[1]);
+  assert_equals(sheet.cssRules.length, 2);
+  assert_equals(sheet.cssRules[0].cssText, redStyleTexts[1]);
+
+  const sheet2 = document.createEmptyCSSStyleSheet({});
+  assert_equals(sheet2.title, "")
+  assert_equals(sheet2.ownerNode, null);
+  assert_equals(sheet2.ownerRule, null);
+  assert_equals(sheet2.media.length, 0);
+  assert_false(sheet2.disabled);
+  assert_equals(sheet2.cssRules.length, 0);
+
+  sheet2.insertRule(redStyleTexts[1]);
+  assert_equals(sheet2.cssRules.length, 1);
+  assert_equals(sheet2.cssRules[0].cssText, redStyleTexts[1]);
+
+  sheet2.deleteRule(0);
+  assert_equals(sheet2.cssRules.length, 0);
+
+const sheet3 = document.createEmptyCSSStyleSheet();
+  assert_equals(sheet3.title, "")
+  assert_equals(sheet3.ownerNode, null);
+  assert_equals(sheet3.ownerRule, null);
+  assert_equals(sheet3.media.length, 0);
+  assert_false(sheet3.disabled);
+  assert_equals(sheet3.cssRules.length, 0);
+
+  sheet3.insertRule(redStyleTexts[1]);
+  assert_equals(sheet3.cssRules.length, 1);
+  assert_equals(sheet3.cssRules[0].cssText, redStyleTexts[1]);
+
+  sheet3.deleteRule(0);
+  assert_equals(sheet3.cssRules.length, 0);
+}, 'Document.createEmptyCSSStyleSheet produces empty CSSStyleSheet');
+
 promise_test(() => {
   const promise_sheet = document.createCSSStyleSheet(redStyleTexts[0], {title: "Red", disabled: true, media: "screen, print"});
   return promise_sheet.then(function(sheet) {

third_party/WebKit/LayoutTests/webexposed/global-interface-listing-expected.txt

@@ -1635,6 +1635,7 @@ interface Document : Node
     method createDocumentFragment
     method createElement
     method createElementNS
+    method createEmptyCSSStyleSheet
     method createEvent
     method createExpression
     method createNSResolver

third_party/blink/renderer/core/dom/document.cc

@@ -1144,6 +1144,20 @@ ScriptPromise Document::createCSSStyleSheet(ScriptState* script_state,
                              ScriptValue::From(script_state, sheet));
 }
 
+CSSStyleSheet* Document::createEmptyCSSStyleSheet(
+    ScriptState* script_state,
+    const CSSStyleSheetInit& options,
+    ExceptionState& exception_state) {
+  return CSSStyleSheet::Create(*this, options, exception_state);
+}
+
+CSSStyleSheet* Document::createEmptyCSSStyleSheet(
+    ScriptState* script_state,
+    ExceptionState& exception_state) {
+  return Document::createEmptyCSSStyleSheet(script_state, CSSStyleSheetInit(),
+                                            exception_state);
+}
+
 ScriptValue Document::registerElement(ScriptState* script_state,
                                       const AtomicString& name,
                                       const ElementRegistrationOptions& options,

third_party/blink/renderer/core/dom/document.h

@@ -362,6 +362,12 @@ class CORE_EXPORT Document : public ContainerNode,
   Element* CreateRawElement(const QualifiedName&,
                             const CreateElementFlags = CreateElementFlags());
 
+  CSSStyleSheet* createEmptyCSSStyleSheet(ScriptState*,
+                                          const CSSStyleSheetInit&,
+                                          ExceptionState&);
+
+  CSSStyleSheet* createEmptyCSSStyleSheet(ScriptState*, ExceptionState&);
+
   ScriptPromise createCSSStyleSheet(ScriptState*,
                                     const String&,
                                     ExceptionState&);

third_party/blink/renderer/core/dom/document.idl

@@ -76,6 +76,8 @@ typedef (HTMLScriptElement or SVGScriptElement) HTMLOrSVGScriptElement;
     [NewObject] Range createRange();
 
     [CallWith=ScriptState, NewObject, RaisesException, RuntimeEnabled=ConstructableStylesheets] Promise<CSSStyleSheet> createCSSStyleSheet(DOMString text, optional CSSStyleSheetInit options);
+    [CallWith=ScriptState, NewObject, RaisesException, RuntimeEnabled=ConstructableStylesheets] CSSStyleSheet createEmptyCSSStyleSheet(optional CSSStyleSheetInit options);
+
 
     // NodeFilter.SHOW_ALL = 0xFFFFFFFF
     [NewObject] NodeIterator createNodeIterator(Node root, optional unsigned long whatToShow = 0xFFFFFFFF, optional NodeFilter? filter = null);