Unify paren handling in (Pre)Parser::ParseExpressionOrLabelledStatement.

src/ast.cc

Index: src/ast.cc
diff --git a/src/ast.cc b/src/ast.cc
index 1a9919b5aa52c0343d60cac4cffd4dcf2ee4d24e..175625727dd03d9401b79580da2a61298cb190a9 100644
--- a/src/ast.cc
+++ b/src/ast.cc
@@ -82,6 +82,16 @@ bool Expression::IsUndefinedLiteral(Isolate* isolate) {
 }
 
 
+bool Expression::IsIdentifier() {
+  return (AsVariableProxy() != NULL && !AsVariableProxy()->is_this());
+}
+
+
+bool Expression::IsIdentifierNamed(String* name) {
+  return (AsVariableProxy() != NULL && AsVariableProxy()->name()->Equals(name));
+}
+
+
 VariableProxy::VariableProxy(Zone* zone, Variable* var, int position)
     : Expression(zone, position),
       name_(var->name()),