Add another check to be sure non-negative smi fits into Uint32 range.

Review URL: http://codereview.chromium.org/3546003

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@5558 ce2b1a6d-e550-0410-aec6-3dcde31c8c00

src/x64/ic-x64.cc

@@ -894,6 +894,7 @@ void KeyedLoadIC::GenerateIndexedInterceptor(MacroAssembler* masm) {
   __ JumpIfSmi(rdx, &slow);
 
   // Check that the key is an array index, that is Uint32.
+  STATIC_ASSERT(kSmiValueSize <= 32);
   __ JumpIfNotPositiveSmi(rax, &slow);
 
   // Get the map of the receiver.