Fix map check removal issue in r13488.

src/hydrogen-instructions.cc

Index: src/hydrogen-instructions.cc
diff --git a/src/hydrogen-instructions.cc b/src/hydrogen-instructions.cc
index 9c808c78f2e74e5f94649a5e0b9b369d82b38607..0bf208b733b48514c6c5468376c2ee8a66122c15 100644
--- a/src/hydrogen-instructions.cc
+++ b/src/hydrogen-instructions.cc
@@ -1173,7 +1173,7 @@ void HCheckMaps::SetSideEffectDominator(GVNFlag side_effect,
   // 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;