Fix HCheckSmiOrInt32 fake observed representation.

Review URL: https://codereview.chromium.org/12259008

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@13694 ce2b1a6d-e550-0410-aec6-3dcde31c8c00

src/hydrogen-instructions.h

@@ -2819,6 +2819,10 @@ class HCheckSmiOrInt32: public HUnaryOperation {
   }
   virtual void InferRepresentation(HInferRepresentation* h_infer);
 
+  virtual Representation observed_input_representation(int index) {
+    return Representation::Integer32();
+  }
+
   virtual HValue* Canonicalize() {
     if (representation().IsTagged() && !type().IsSmi()) {
       return this;