Fix MSVC warnings about possible value truncation.

src/gasp.cc

 // Copyright (c) 2009 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "gasp.h"
 
 // gasp - Grid-fitting And Scan-conversion Procedure
 // http://www.microsoft.com/opentype/otspec/gasp.htm
 
 #define DROP_THIS_TABLE \
@@ skipping 66 matching lines @@
   return true;
 }
 
 bool ots_gasp_should_serialise(OpenTypeFile *file) {
   return file->gasp != NULL;
 }
 
 bool ots_gasp_serialise(OTSStream *out, OpenTypeFile *file) {
   const OpenTypeGASP *gasp = file->gasp;
 
-  if (!out->WriteU16(gasp->version) ||
-      !out->WriteU16(gasp->gasp_ranges.size())) {
+  const uint16_t num_ranges = static_cast<uint16_t>(gasp->gasp_ranges.size());
+  if (num_ranges != gasp->gasp_ranges.size() ||
+      !out->WriteU16(gasp->version) ||
+      !out->WriteU16(num_ranges)) {
     return OTS_FAILURE();
   }
 
-  for (unsigned i = 0; i < gasp->gasp_ranges.size(); ++i) {
+  for (uint16_t i = 0; i < num_ranges; ++i) {
     if (!out->WriteU16(gasp->gasp_ranges[i].first) ||
         !out->WriteU16(gasp->gasp_ranges[i].second)) {
       return OTS_FAILURE();
     }
   }
 
   return true;
 }
 
 void ots_gasp_free(OpenTypeFile *file) {
   delete file->gasp;
 }
 
 }  // namespace ots