Fix a few -Wignored-qualifiers warnings.

src/compiler/frame.h

 // Copyright 2014 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef V8_COMPILER_FRAME_H_
 #define V8_COMPILER_FRAME_H_
 
 #include "src/bit-vector.h"
 #include "src/frames.h"
 
@@ skipping 210 matching lines @@
 
 // Encapsulates the mutable state maintained during code generation about the
 // current function's frame.
 class FrameAccessState : public ZoneObject {
  public:
   explicit FrameAccessState(Frame* const frame)
       : frame_(frame), access_frame_with_fp_(false), sp_delta_(0) {
     SetFrameAccessToDefault();
   }
 
-  Frame* const frame() const { return frame_; }
+  Frame* frame() const { return frame_; }
 
   int sp_delta() const { return sp_delta_; }
   void ClearSPDelta() { sp_delta_ = 0; }
   void IncreaseSPDelta(int amount) { sp_delta_ += amount; }
 
   bool access_frame_with_fp() const { return access_frame_with_fp_; }
   void SetFrameAccessToDefault();
   void SetFrameAccessToFP() { access_frame_with_fp_ = true; }
   void SetFrameAccessToSP() { access_frame_with_fp_ = false; }
 
   // Get the frame offset for a given spill slot. The location depends on the
   // calling convention and the specific frame layout, and may thus be
   // architecture-specific. Negative spill slots indicate arguments on the
   // caller's frame.
   FrameOffset GetFrameOffset(int spill_slot) const;
 
  private:
   Frame* const frame_;
   bool access_frame_with_fp_;
   int sp_delta_;
 };
 }  // namespace compiler
 }  // namespace internal
 }  // namespace v8
 
 #endif  // V8_COMPILER_FRAME_H_