Clean up code stubs and ensure distinct major keys.

src/x64/code-stubs-x64.h

Index: src/x64/code-stubs-x64.h
diff --git a/src/x64/code-stubs-x64.h b/src/x64/code-stubs-x64.h
index bcbf220394116ec8ea648d5e5157547994634340..c8e3835dc46348349ce56b03d37dc87e9b91b6a4 100644
--- a/src/x64/code-stubs-x64.h
+++ b/src/x64/code-stubs-x64.h
@@ -110,7 +110,7 @@ class NameDictionaryLookupStub: public PlatformCodeStub {
       NameDictionary::kHeaderSize +
       NameDictionary::kElementsStartIndex * kPointerSize;
 
-  Major MajorKey() const { return NameDictionaryLookup; }
+  virtual inline Major MajorKey() const FINAL OVERRIDE;
 
   Register dictionary() const {
     return Register::from_code(DictionaryBits::decode(minor_key_));
@@ -334,7 +334,7 @@ class RecordWriteStub: public PlatformCodeStub {
     kUpdateRememberedSetOnNoNeedToInformIncrementalMarker
   };
 
-  Major MajorKey() const { return RecordWrite; }
+  virtual inline Major MajorKey() const FINAL OVERRIDE;
 
   void Generate(MacroAssembler* masm);
   void GenerateIncremental(MacroAssembler* masm, Mode mode);