HasNonSmiUse should ignore tagged uses

R=verwaest@chromium.org

Review URL: https://chromiumcodereview.appspot.com/21105006

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

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@15950 ce2b1a6d-e550-0410-aec6-3dcde31c8c00

src/hydrogen-instructions.cc

@@ -4375,7 +4375,11 @@ bool HValue::HasNonSmiUse() {
     // We check for observed_input_representation elsewhere.
     Representation use_rep =
         it.value()->RequiredInputRepresentation(it.index());
-    if (!use_rep.IsNone() && !use_rep.IsSmi()) return true;
+    if (!use_rep.IsNone() &&
+        !use_rep.IsSmi() &&
+        !use_rep.IsTagged()) {
+      return true;
+    }
   }
   return false;
 }