Add blink_perf.editing

tools/perf/benchmarks/blink_perf.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 os
 
 from core import path_util
 from core import perf_benchmark
 
 from telemetry import benchmark
@@ skipping 218 matching lines @@
     # be set on each page.
     for page in story_set:
       page.skipped_gpus = []
     return story_set
 
 
 class BlinkPerfDOM(_BlinkPerfBenchmark):
   tag = 'dom'
   subdir = 'DOM'
 
+class BlinkPerfEditing(_BlinkPerfBenchmark):
+  tag = 'editing'
+  subdir = 'Editing'
 
 class BlinkPerfEvents(_BlinkPerfBenchmark):
   tag = 'events'
   subdir = 'Events'
 
 
 @benchmark.Disabled('win8')  # http://crbug.com/462350
 class BlinkPerfLayout(_BlinkPerfBenchmark):
   tag = 'layout'
   subdir = 'Layout'
@@ skipping 51 matching lines @@
 
   def CreateStorySet(self, options):
     path = os.path.join(BLINK_PERF_BASE_DIR, self.subdir)
     return CreateStorySetFromPath(
         path, SKIPPED_FILE,
         shared_page_state_class=_SharedPywebsocketPageState)
 
   @classmethod
   def ShouldDisable(cls, possible_browser):
     return cls.IsSvelte(possible_browser)  # http://crbug.com/551950