Added support for improvement_direction to relevant values, which is propogated to chartjson.

tools/perf/metrics/v8_object_stats.py

 # Copyright 2013 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.
 
 import json
 import logging
 
 from metrics import Metric
 from telemetry.value import scalar
 
@@ skipping 212 matching lines @@
       logging.warning('No V8 object stats from website: ' + page.display_name)
 
   def AddResults(self, tab, results):
     """Add results for this page to the results object."""
     assert self._results != None, 'Must call Stop() first'
     for counter_name in self._results:
       description = DESCRIPTIONS.get(counter_name)
       display_name = counter_name.replace('.', '_')
       results.AddValue(scalar.ScalarValue(
           results.current_page, display_name, 'kb',
-          self._results[counter_name] / 1024.0, description=description))
+          self._results[counter_name] / 1024.0, description=description,
+          higher_is_better=False))