Use Unique<Map> in HTransitionElementsKind.

src/mips/lithium-mips.h

Index: src/mips/lithium-mips.h
diff --git a/src/mips/lithium-mips.h b/src/mips/lithium-mips.h
index 4cfa128b5da5b46e55bf9e4a31c2ad8f967c6b38..7c22ae89410a733bdc9dfeea647c5403b7834e85 100644
--- a/src/mips/lithium-mips.h
+++ b/src/mips/lithium-mips.h
@@ -2250,8 +2250,10 @@ class LTransitionElementsKind V8_FINAL : public LTemplateInstruction<0, 1, 1> {
 
   virtual void PrintDataTo(StringStream* stream) V8_OVERRIDE;
 
-  Handle<Map> original_map() { return hydrogen()->original_map(); }
-  Handle<Map> transitioned_map() { return hydrogen()->transitioned_map(); }
+  Handle<Map> original_map() { return hydrogen()->original_map().handle(); }
+  Handle<Map> transitioned_map() {
+    return hydrogen()->transitioned_map().handle();
+  }
   ElementsKind from_kind() { return hydrogen()->from_kind(); }
   ElementsKind to_kind() { return hydrogen()->to_kind(); }
 };