RFC: Make BisonCSSParser purely stack allocated.

Source/core/css/parser/BisonCSSParser.h

Index: Source/core/css/parser/BisonCSSParser.h
diff --git a/Source/core/css/parser/BisonCSSParser.h b/Source/core/css/parser/BisonCSSParser.h
index 90c9c7ecbec74d20ef60de4de218d47a6884499b..4a847d80be55091f999769130c6cbb37c30d2438 100644
--- a/Source/core/css/parser/BisonCSSParser.h
+++ b/Source/core/css/parser/BisonCSSParser.h
@@ -78,10 +78,10 @@ struct CSSParserLocation {
 };
 
 class BisonCSSParser {
+    STACK_ALLOCATED();
     friend inline int cssyylex(void*, BisonCSSParser*);
-
 public:
-    BisonCSSParser(const CSSParserContext&);
+    explicit BisonCSSParser(const CSSParserContext&);
     ~BisonCSSParser();
 
     void rollbackLastProperties(int num);