migrate skpdiff to tools

tools/skpdiff/SkDiffContext.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 "SkBitmap.h"
 #include "SkImageDecoder.h"
 #include "SkOSFile.h"
@@ skipping 162 matching lines @@
             stream.writeText("            \"diffs\": [\n");
             for (int diffIndex = 0; diffIndex < currentRecord->fDiffs.count(); diffIndex++) {
                 DiffData& data = currentRecord->fDiffs[diffIndex];
                 stream.writeText("                {\n");
 
                     stream.writeText("                    \"differName\": \"");
                     stream.writeText(data.fDiffName);
                     stream.writeText("\",\n");
 
                     stream.writeText("                    \"result\": ");
-                    stream.writeScalarAsText(data.fResult);
+                    stream.writeScalarAsText((SkScalar)data.fResult);
                     stream.writeText(",\n");
 
                     stream.writeText("                    \"pointsOfInterest\": [\n");
                     for (int poiIndex = 0; poiIndex < data.fPointsOfInterest.count(); poiIndex++) {
                         SkIPoint poi = data.fPointsOfInterest[poiIndex];
                         stream.writeText("                        [");
                         stream.writeDecAsText(poi.x());
                         stream.writeText(",");
                         stream.writeDecAsText(poi.y());
                         stream.writeText("]");
@@ skipping 29 matching lines @@
     }
     stream.writeText("    ]\n");
     if (useJSONP) {
         stream.writeText("};\n");
     }
     else
     {
         stream.writeText("}\n");
     }
 }