use better heuristic for maxcharwidth

public/blink_skia_config.gypi

 # Copyright 2014 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.
 {
   'variables': {
 
     # Place defines here that require significant Blink rebaselining, or that
     # are otherwise best removed in Blink and then rolled into Chromium.
     # Defines should be in single quotes and a comma must appear after every one.
     # DO NOT remove the define until you are ready to rebaseline, and
     # AFTER the flag has been removed from skia.gyp in Chromium.
     'blink_skia_defines': [
           'SK_FM_NEW_MATCH_FAMILY_STYLE_CHARACTER=1',
+          'SK_USE_SCALED_FONTMETRICS',
     ],
   },
 }