Revert of Disabled the v8.todomvc reference build due to missing clock sync markers

tools/perf/benchmarks/v8.py

 # 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.
 import os
 
 from core import path_util
 from core import perf_benchmark
 from page_sets import google_pages
 
 from benchmarks import v8_helper
@@ skipping 97 matching lines @@
 
   @classmethod
   def ValueCanBeAddedPredicate(cls, value, _):
     return 'v8' in value.name
 
   @classmethod
   def ShouldTearDownStateAfterEachStoryRun(cls):
     return True
 
 
-# Disabled on reference builds due to http://crbug.com/646925
-@benchmark.Disabled('reference')
 class V8TodoMVC(perf_benchmark.PerfBenchmark):
   """Measures V8 Execution metrics on the TodoMVC examples."""
   page_set = page_sets.TodoMVCPageSet
 
   def CreateTimelineBasedMeasurementOptions(self):
     return CreateV8TimelineBasedMeasurementOptions()
 
   @classmethod
   def Name(cls):
     return 'v8.todomvc'
@@ skipping 96 matching lines @@
       return True
     # http://crbug.com/623576
     if (possible_browser.platform.GetDeviceTypeName() == 'Nexus 5' or
         possible_browser.platform.GetDeviceTypeName() == 'Nexus 7'):
       return True
     return False
 
   @classmethod
   def ShouldTearDownStateAfterEachStoryRun(cls):
     return True