Improve JSON stringifier's escape check.

src/parser.cc

Index: src/parser.cc
diff --git a/src/parser.cc b/src/parser.cc
index 29b1fe74c6058a344f12d75e5d9407f0b86d1ae6..d620457217b2a637fa3c0a754dec7268d4e1488b 100644
--- a/src/parser.cc
+++ b/src/parser.cc
@@ -257,8 +257,13 @@ Handle<String> Parser::LookupSymbol(int symbol_id) {
   if (static_cast<unsigned>(symbol_id)
       >= static_cast<unsigned>(symbol_cache_.length())) {
     if (scanner().is_literal_ascii()) {
-      return isolate()->factory()->LookupOneByteSymbol(
+      Handle<String> symbol = isolate()->factory()->LookupOneByteSymbol(
           Vector<const uint8_t>::cast(scanner().literal_ascii_string()));
+      if (scanner().is_literal_printable_ascii() &&
+          symbol->map() == isolate()->heap()->ascii_symbol_map()) {
+        symbol->set_map(isolate()->heap()->printable_ascii_symbol_map());
+      }
+      return symbol;
     } else {
       return isolate()->factory()->LookupTwoByteSymbol(
           scanner().literal_utf16_string());
@@ -3610,7 +3615,7 @@ Expression* Parser::ParsePrimaryExpression(bool* ok) {
 
     case Token::NUMBER: {
       Consume(Token::NUMBER);
-      ASSERT(scanner().is_literal_ascii());
+      ASSERT(scanner().is_literal_printable_ascii());
       double value = StringToDouble(isolate()->unicode_cache(),
                                     scanner().literal_ascii_string(),
                                     ALLOW_HEX | ALLOW_OCTALS);
@@ -4086,7 +4091,7 @@ Expression* Parser::ParseObjectLiteral(bool* ok) {
       }
       case Token::NUMBER: {
         Consume(Token::NUMBER);
-        ASSERT(scanner().is_literal_ascii());
+        ASSERT(scanner().is_literal_printable_ascii());
         double value = StringToDouble(isolate()->unicode_cache(),
                                       scanner().literal_ascii_string(),
                                       ALLOW_HEX | ALLOW_OCTALS);
@@ -4839,7 +4844,8 @@ Handle<String> Parser::ParseIdentifierNameOrGetOrSet(bool* is_get,
                                                      bool* ok) {
   Handle<String> result = ParseIdentifierName(ok);
   if (!*ok) return Handle<String>();
-  if (scanner().is_literal_ascii() && scanner().literal_length() == 3) {
+  if (scanner().is_literal_printable_ascii() &&
+      scanner().literal_length() == 3) {
     const char* token = scanner().literal_ascii_string().start();
     *is_get = strncmp(token, "get", 3) == 0;
     *is_set = !*is_get && strncmp(token, "set", 3) == 0;