Fixing bug caused by missing smi-tag.

Review URL: http://codereview.chromium.org/8240007

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@9598 ce2b1a6d-e550-0410-aec6-3dcde31c8c00

src/x64/stub-cache-x64.cc

@@ -3799,6 +3799,8 @@ void KeyedStoreStubCompiler::GenerateStoreFastDoubleElement(
   __ jmp(ic_force_generic, RelocInfo::CODE_TARGET);
 
   __ bind(&transition_elements_kind);
+  // Restore smi-tagging of rcx.
+  __ Integer32ToSmi(rcx, rcx);
   Handle<Code> ic_miss = masm->isolate()->builtins()->KeyedStoreIC_Miss();
   __ jmp(ic_miss, RelocInfo::CODE_TARGET);
 }