Fixed HMul::Canonicalize() to support SMI

Same idea for HDiv when the right oeprand is 1

BUG=
R=jkummerow@chromium.org

Review URL: https://codereview.chromium.org/23176002

Patch from Weiliang Lin <weiliang.lin2@gmail.com>.

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@16364 ce2b1a6d-e550-0410-aec6-3dcde31c8c00

src/hydrogen-instructions.cc

@@ -1243,6 +1243,7 @@ HValue* HMod::Canonicalize() {
 
 
 HValue* HDiv::Canonicalize() {
+  if (IsIdentityOperation(left(), right(), 1)) return left();
   return this;
 }
 

src/property-details.h

@@ -148,7 +148,7 @@ class Representation {
   bool IsHeapObject() const { return kind_ == kHeapObject; }
   bool IsExternal() const { return kind_ == kExternal; }
   bool IsSpecialization() const {
-    return kind_ == kInteger32 || kind_ == kDouble;
+    return kind_ == kInteger32 || kind_ == kDouble || kind_ == kSmi;
   }
   const char* Mnemonic() const;