JSON.parse improvement. Call "LookupSymbol" rather than "NewString"

for property string tokens.
Review URL: http://codereview.chromium.org/7004016

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@7859 ce2b1a6d-e550-0410-aec6-3dcde31c8c00

src/parser.cc

@@ -4084,6 +4084,21 @@ Handle<String> JsonParser::GetString() {
 }
 
 
+Handle<String> JsonParser::GetSymbol() {
+  int literal_length = scanner_.literal_length();
+  if (literal_length == 0) {
+    return isolate()->factory()->empty_string();
+  }
+  if (scanner_.is_literal_ascii()) {
+    return isolate()->factory()->LookupAsciiSymbol(
+        scanner_.literal_ascii_string());
+  } else {
+    return isolate()->factory()->LookupTwoByteSymbol(
+        scanner_.literal_uc16_string());
+  }
+}
+
+
 // Parse any JSON value.
 Handle<Object> JsonParser::ParseJsonValue() {
   Token::Value token = scanner_.Next();
@@ -4125,7 +4140,7 @@ Handle<Object> JsonParser::ParseJsonObject() {
       if (scanner_.Next() != Token::STRING) {
         return ReportUnexpectedToken();
       }
-      Handle<String> key = GetString();
+      Handle<String> key = GetSymbol();
       if (scanner_.Next() != Token::COLON) {
         return ReportUnexpectedToken();
       }

src/parser.h

@@ -814,6 +814,8 @@ class JsonParser BASE_EMBEDDED {
   Handle<Object> ReportUnexpectedToken() { return Handle<Object>::null(); }
   // Converts the currently parsed literal to a JavaScript String.
   Handle<String> GetString();
+  // Converts the currently parsed literal to a JavaScript Symbol String.
+  Handle<String> GetSymbol();
 
   Isolate* isolate_;
   JsonScanner scanner_;