fix more 64bit warnings

src/utils/SkLuaCanvas.cpp

 /*
  * Copyright 2013 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #include "SkLuaCanvas.h"
 #include "SkLua.h"
 
@@ skipping 39 matching lines @@
     switch (enc) {
         case SkPaint::kUTF8_TextEncoding:
             this->pushString((const char*)text, length, "text");
             break;
         case SkPaint::kUTF16_TextEncoding: {
             SkString str;
             str.setUTF16((const uint16_t*)text, length);
             this->pushString(str, "text");
         } break;
         case SkPaint::kGlyphID_TextEncoding:
-            this->pushArrayU16((const uint16_t*)text, length >> 1, "glyphs");
+            this->pushArrayU16((const uint16_t*)text, SkToInt(length >> 1),
+                               "glyphs");
             break;
         case SkPaint::kUTF32_TextEncoding:
             break;
     }
 }
 
 ///////////////////////////////////////////////////////////////////////////////
 
 void SkLuaCanvas::pushThis() {
     SkLua(fL).pushCanvas(this);
@@ skipping 209 matching lines @@
                                  const SkColor colors[], SkXfermode* xmode,
                                  const uint16_t indices[], int indexCount,
                                  const SkPaint& paint) {
     AUTO_LUA("drawVertices");
     lua.pushPaint(paint, "paint");
 }
 
 void SkLuaCanvas::drawData(const void* data, size_t length) {
     AUTO_LUA("drawData");
 }