[runtime] Support Proxy setPrototypeOf trap

src/runtime/runtime-proxy.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/factory.h"
 #include "src/objects-inl.h"
 
@@ skipping 13 matching lines @@
   if (target->IsJSProxy() && !JSProxy::cast(*target)->has_handler()) {
     // TODO(cbruni): Use better error message.
     THROW_NEW_ERROR_RETURN_FAILURE(
         isolate, NewTypeError(MessageTemplate::kProxyTargetNonObject));
   }
   if (!handler->IsSpecObject()) {
     THROW_NEW_ERROR_RETURN_FAILURE(
         isolate, NewTypeError(MessageTemplate::kProxyHandlerNonObject));
   }
   if (handler->IsJSProxy() && !JSProxy::cast(*handler)->has_handler()) {
-    // TODO(cbruni): Use better error message.
-    THROW_NEW_ERROR_RETURN_FAILURE(
-        isolate, NewTypeError(MessageTemplate::kProxyHandlerNonObject));
+    THROW_NEW_ERROR_RETURN_FAILURE(isolate,
+                                   NewTypeError(MessageTemplate::kProtoNotSet));
   }
   instance->set_target(*target);
   instance->set_handler(*handler);
   instance->set_hash(isolate->heap()->undefined_value(), SKIP_WRITE_BARRIER);
   return *instance;
 }
 
 
 RUNTIME_FUNCTION(Runtime_CreateJSFunctionProxy) {
   HandleScope scope(isolate);
@@ skipping 44 matching lines @@
 
 RUNTIME_FUNCTION(Runtime_GetConstructTrap) {
   SealHandleScope shs(isolate);
   DCHECK(args.length() == 1);
   CONVERT_ARG_CHECKED(JSFunctionProxy, proxy, 0);
   return proxy->construct_trap();
 }
 
 }  // namespace internal
 }  // namespace v8