Refactor RuleFeatureSet to simplify iteration over CSS Selectors when collecting data.

Source/core/css/CSSDefaultStyleSheets.cpp

Index: Source/core/css/CSSDefaultStyleSheets.cpp
diff --git a/Source/core/css/CSSDefaultStyleSheets.cpp b/Source/core/css/CSSDefaultStyleSheets.cpp
index 9375aa4b8e4026fd2d8d31db74cb10e4dfb1721e..0197c212002c4ecc05024cc97523ce093ab2407e 100644
--- a/Source/core/css/CSSDefaultStyleSheets.cpp
+++ b/Source/core/css/CSSDefaultStyleSheets.cpp
@@ -160,7 +160,7 @@ void CSSDefaultStyleSheets::ensureDefaultStyleSheetsForElement(Element* element,
         changedDefaultStyle = true;
     }
 
-    ASSERT(defaultStyle->features().idsInRules.isEmpty());
+    ASSERT(!defaultStyle->features().hasIdsInSelectors());
     ASSERT(defaultStyle->features().siblingRules.isEmpty());
 }