Cleanup StringAddFlags.

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 af72f59cbf4250fad3629c3707d77b31dc77512b..e430bf2c80540350ea61dc9edd46f9635f9b659e 100644
--- a/src/x64/code-stubs-x64.h
+++ b/src/x64/code-stubs-x64.h
@@ -134,21 +134,6 @@ class StringHelper : public AllStatic {
 };
 
 
-// Flag that indicates how to generate code for the stub StringAddStub.
-enum StringAddFlags {
-  NO_STRING_ADD_FLAGS = 1 << 0,
-  // Omit left string check in stub (left is definitely a string).
-  NO_STRING_CHECK_LEFT_IN_STUB = 1 << 1,
-  // Omit right string check in stub (right is definitely a string).
-  NO_STRING_CHECK_RIGHT_IN_STUB = 1 << 2,
-  // Stub needs a frame before calling the runtime
-  ERECT_FRAME = 1 << 3,
-  // Omit both string checks in stub.
-  NO_STRING_CHECK_IN_STUB =
-      NO_STRING_CHECK_LEFT_IN_STUB | NO_STRING_CHECK_RIGHT_IN_STUB
-};
-
-
 class StringAddStub: public PlatformCodeStub {
  public:
   explicit StringAddStub(StringAddFlags flags) : flags_(flags) {}