Fix map check removal issue in r13488.

src/hydrogen-instructions.cc

 // Copyright 2012 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 1155 matching lines @@
   }
 }
 
 
 void HCheckMaps::SetSideEffectDominator(GVNFlag side_effect,
                                         HValue* dominator) {
   ASSERT(side_effect == kChangesMaps);
   // TODO(mstarzinger): For now we specialize on HStoreNamedField, but once
   // type information is rich enough we should generalize this to any HType
   // for which the map is known.
-  if (dominator->IsStoreNamedField()) {
+  if (HasNoUses() && dominator->IsStoreNamedField()) {
     HStoreNamedField* store = HStoreNamedField::cast(dominator);
     Handle<Map> map = store->transition();
     if (map.is_null() || store->object() != value()) return;
     for (int i = 0; i < map_set()->length(); i++) {
       if (map.is_identical_to(map_set()->at(i))) {
         DeleteAndReplaceWith(NULL);
         return;
       }
     }
   }
@@ skipping 1647 matching lines @@
 
 
 void HCheckFunction::Verify() {
   HInstruction::Verify();
   ASSERT(HasNoUses());
 }
 
 #endif
 
 } }  // namespace v8::internal