Add fast-path for propagated variable changes (WIP)

third_party/WebKit/Source/core/css/resolver/StyleBuilderCustom.cpp

Index: third_party/WebKit/Source/core/css/resolver/StyleBuilderCustom.cpp
diff --git a/third_party/WebKit/Source/core/css/resolver/StyleBuilderCustom.cpp b/third_party/WebKit/Source/core/css/resolver/StyleBuilderCustom.cpp
index d4f085bcd3c6ff89be5f7899d8d47384ff08ba4d..90f91fdb85b1b0c9dc899b0a8b229d18ed181322 100644
--- a/third_party/WebKit/Source/core/css/resolver/StyleBuilderCustom.cpp
+++ b/third_party/WebKit/Source/core/css/resolver/StyleBuilderCustom.cpp
@@ -120,9 +120,13 @@ void StyleBuilder::applyProperty(CSSPropertyID id,
                                                        omitAnimationTainted);
     applyProperty(id, state, *resolvedValue);
 
-    if (!state.style()->hasVariableReferenceFromNonInheritedProperty() &&
-        !CSSPropertyMetadata::isInheritedProperty(id))
+    // TODO(sashab): Clear this flag if all properties are set back to
+    // non-variable references.
+    if (CSSPropertyMetadata::isInheritedProperty(id))
+      state.style()->setHasVariableReferenceFromInheritedProperty();
+    else
       state.style()->setHasVariableReferenceFromNonInheritedProperty();
+
     return;
   }