Don't ignore CascadeOrigin::kNone for <summary> use-counter

I forgot to handle CascadeOrigin::kNone, which means the subsequent
call to priority.GetPosition() would always return zero, and we would
access the wrong value (and possibly crash).

Handle that case, and add a more detailed test which verifies each
origin.

Fixed: 1108019
Change-Id: I298c12ed56231b27f3ce505911db5e3fe0c2a16e
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2310535Reviewed-by: Xiaocheng Hu <xiaochengh@chromium.org>
Commit-Queue: Anders Hartvoll Ruud <andruud@chromium.org>
Cr-Commit-Position: refs/heads/master@{#790979}

third_party/blink/renderer/core/css/resolver/style_cascade.cc

@@ -945,7 +945,7 @@ void StyleCascade::MaybeUseCountSummaryDisplayBlock() {
   if (!state_.GetElement().HasTagName(html_names::kSummaryTag))
     return;
   CascadePriority priority = map_.At(CSSPropertyName(CSSPropertyID::kDisplay));
-  if (priority.GetOrigin() == CascadeOrigin::kUserAgent)
+  if (priority.GetOrigin() <= CascadeOrigin::kUserAgent)
     return;
   const CSSValue* value = ValueAt(match_result_, priority.GetPosition());
   if (auto* identifier = DynamicTo<CSSIdentifierValue>(value)) {

third_party/blink/renderer/core/css/resolver/style_cascade_test.cc

@@ -3365,4 +3365,53 @@ TEST_F(StyleCascadeTest, MaxSubstitutionTokens) {
             cascade.ComputedValue("--above-limit-reference-fallback"));
 }
 
+TEST_F(StyleCascadeTest, UseCountSummary) {
+  const auto feature = WebFeature::kSummaryElementWithDisplayBlockAuthorRule;
+
+  Element* summary = GetDocument().CreateRawElement(html_names::kSummaryTag);
+  GetDocument().body()->AppendChild(summary);
+
+  {
+    ASSERT_FALSE(GetDocument().IsUseCounted(feature));
+
+    TestCascade cascade(GetDocument(), summary);
+    cascade.Apply();
+    EXPECT_FALSE(GetDocument().IsUseCounted(feature));
+  }
+  {
+    ASSERT_FALSE(GetDocument().IsUseCounted(feature));
+
+    TestCascade cascade(GetDocument(), summary);
+    cascade.Add("color:green");
+    cascade.Apply();
+    EXPECT_FALSE(GetDocument().IsUseCounted(feature));
+  }
+  {
+    ASSERT_FALSE(GetDocument().IsUseCounted(feature));
+
+    TestCascade cascade(GetDocument(), summary);
+    cascade.Add("display:block", CascadeOrigin::kUserAgent);
+    cascade.Apply();
+    EXPECT_FALSE(GetDocument().IsUseCounted(feature));
+  }
+  {
+    ASSERT_FALSE(GetDocument().IsUseCounted(feature));
+
+    TestCascade cascade(GetDocument(), summary);
+    cascade.Add("display:block", CascadeOrigin::kUser);
+    cascade.Apply();
+    EXPECT_TRUE(GetDocument().IsUseCounted(feature));
+    GetDocument().ClearUseCounterForTesting(feature);
+  }
+  {
+    ASSERT_FALSE(GetDocument().IsUseCounted(feature));
+
+    TestCascade cascade(GetDocument(), summary);
+    cascade.Add("display:block", CascadeOrigin::kAuthor);
+    cascade.Apply();
+    EXPECT_TRUE(GetDocument().IsUseCounted(feature));
+    GetDocument().ClearUseCounterForTesting(feature);
+  }
+}
+
 }  // namespace blink