Call IsStringLiteral instead of IsPropertyName in VisitObjectLiteral.

src/ast/ast.cc

Index: src/ast/ast.cc
diff --git a/src/ast/ast.cc b/src/ast/ast.cc
index c1b424488a97f3a4b81804bdd6c88168fb4da508..835e2c850a1b74b1256df89c8f5fb00be431cbaa 100644
--- a/src/ast/ast.cc
+++ b/src/ast/ast.cc
@@ -66,12 +66,11 @@ MaterializedLiteral* AstNode::AsMaterializedLiteral() {
 #undef RETURN_NODE
 
 bool Expression::IsSmiLiteral() const {
-  return IsLiteral() && AsLiteral()->value()->IsSmi();
+  return IsLiteral() && AsLiteral()->raw_value()->IsSmi();
 }
 
-
 bool Expression::IsStringLiteral() const {
-  return IsLiteral() && AsLiteral()->value()->IsString();
+  return IsLiteral() && AsLiteral()->raw_value()->IsString();
 }
 
 bool Expression::IsPropertyName() const {