Fast string construct stub (ia32 only for now).

src/runtime.cc

Index: src/runtime.cc
diff --git a/src/runtime.cc b/src/runtime.cc
index f908036469a07699028bc95517926ba648ef6304..2fd5af59c6c4d92b1d2013fd4cb92d57b0f4b746 100644
--- a/src/runtime.cc
+++ b/src/runtime.cc
@@ -5575,6 +5575,14 @@ static Object* Runtime_StringToArray(Arguments args) {
 }
 
 
+static Object* Runtime_NewStringWrapper(Arguments args) {
+  NoHandleAllocation ha;
+  ASSERT(args.length() == 1);
+  CONVERT_CHECKED(String, value, args[0]);
+  return value->ToObject();
+}
+
+
 bool Runtime::IsUpperCaseChar(uint16_t ch) {
   unibrow::uchar chars[unibrow::ToUppercase::kMaxWidth];
   int char_length = to_upper_mapping.get(ch, 0, chars);