Handle string + number in hydrogen.

src/code-stubs-hydrogen.cc

 // Copyright 2012 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 333 matching lines @@
 
 Handle<Code> ToNumberStub::GenerateCode(Isolate* isolate) {
   return DoGenerateCode(isolate, this);
 }
 
 
 template <>
 HValue* CodeStubGraphBuilder<NumberToStringStub>::BuildCodeStub() {
   info()->MarkAsSavesCallerDoubles();
   HValue* number = GetParameter(NumberToStringStub::kNumber);
-  return BuildNumberToString(number);
+  return BuildNumberToString(number, ALLOW_SIDE_EFFECTS);
 }
 
 
 Handle<Code> NumberToStringStub::GenerateCode(Isolate* isolate) {
   return DoGenerateCode(isolate, this);
 }
 
 
 template <>
 HValue* CodeStubGraphBuilder<FastCloneShallowArrayStub>::BuildCodeStub() {
@@ skipping 868 matching lines @@
   return js_function;
 }
 
 
 Handle<Code> FastNewClosureStub::GenerateCode(Isolate* isolate) {
   return DoGenerateCode(isolate, this);
 }
 
 
 } }  // namespace v8::internal