[runtime] Add %ToString and %_ToString and remove the TO_STRING builtin.

src/runtime/runtime-object.cc

 // Copyright 2014 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "src/runtime/runtime-utils.h"
 
 #include "src/arguments.h"
 #include "src/bootstrapper.h"
 #include "src/debug/debug.h"
 #include "src/messages.h"
@@ skipping 1466 matching lines @@
   HandleScope scope(isolate);
   DCHECK_EQ(1, args.length());
   CONVERT_ARG_HANDLE_CHECKED(Object, input, 0);
   Handle<Object> result;
   ASSIGN_RETURN_FAILURE_ON_EXCEPTION(isolate, result,
                                      Object::ToNumber(isolate, input));
   return *result;
 }
 
 
+RUNTIME_FUNCTION(Runtime_ToString) {
+  HandleScope scope(isolate);
+  DCHECK_EQ(1, args.length());
+  CONVERT_ARG_HANDLE_CHECKED(Object, input, 0);
+  Handle<Object> result;
+  ASSIGN_RETURN_FAILURE_ON_EXCEPTION(isolate, result,
+                                     Object::ToString(isolate, input));
+  return *result;
+}
+
+
 RUNTIME_FUNCTION(Runtime_ToName) {
   HandleScope scope(isolate);
   DCHECK_EQ(1, args.length());
   CONVERT_ARG_HANDLE_CHECKED(Object, input, 0);
   Handle<Object> result;
   ASSIGN_RETURN_FAILURE_ON_EXCEPTION(isolate, result,
                                      Object::ToName(isolate, input));
   return *result;
 }
 
@@ skipping 56 matching lines @@
   SealHandleScope scope(isolate);
   DCHECK_EQ(2, args.length());
   CONVERT_ARG_CHECKED(Object, object, 0);
   CONVERT_ARG_CHECKED(Object, prototype, 1);
   return isolate->heap()->ToBoolean(
       object->HasInPrototypeChain(isolate, prototype));
 }
 
 }  // namespace internal
 }  // namespace v8