Clean up some uses of Failures and MaybeObjects.

src/x64/macro-assembler-x64.h

Index: src/x64/macro-assembler-x64.h
diff --git a/src/x64/macro-assembler-x64.h b/src/x64/macro-assembler-x64.h
index a2163642d5c0e841248df843eac860d8c8f7a5d0..9dab85f0dddece43bc0ddb4db73a5a2605cc86f3 100644
--- a/src/x64/macro-assembler-x64.h
+++ b/src/x64/macro-assembler-x64.h
@@ -1506,13 +1506,6 @@ class MacroAssembler: public Assembler {
                                  Register scratch,
                                  AllocationFlags flags);
 
-  // Helper for PopHandleScope.  Allowed to perform a GC and returns
-  // NULL if gc_allowed.  Does not perform a GC if !gc_allowed, and
-  // possibly returns a failure object indicating an allocation failure.
-  Object* PopHandleScopeHelper(Register saved,
-                               Register scratch,
-                               bool gc_allowed);
-
   // Helper for implementing JumpIfNotInNewSpace and JumpIfInNewSpace.
   void InNewSpace(Register object,
                   Register scratch,