Make SkTDArray accessors const-friendly

src/core/SkPathHeap.cpp

 
 /*
  * Copyright 2011 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 #include "SkPathHeap.h"
 #include "SkPath.h"
 #include "SkStream.h"
@@ skipping 36 matching lines @@
     SkPath* p = (SkPath*)fHeap.allocThrow(sizeof(SkPath));
     new (p) SkPath(path);
     *fPaths.append() = p;
     return fPaths.count();
 }
 
 void SkPathHeap::flatten(SkFlattenableWriteBuffer& buffer) const {
     int count = fPaths.count();
 
     buffer.writeInt(count);
-    SkPath** iter = fPaths.begin();
-    SkPath** stop = fPaths.end();
+    SkPath* const* iter = fPaths.begin();
+    SkPath* const* stop = fPaths.end();
     while (iter < stop) {
         buffer.writePath(**iter);
         iter++;
     }
 }