Update the Blink recipe to use 'webkit_revision' instead of 'webkit_rev'

recipes/chromium.py

 # Copyright (c) 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 sys
 
 import recipe_util  # pylint: disable=F0401
 
 
 # This class doesn't need an __init__ method, so we disable the warning
 # pylint: disable=W0232
 class Chromium(recipe_util.Recipe):
   """Basic Recipe class for Chromium."""
 
   @staticmethod
   def fetch_spec(props):
     url = 'https://chromium.googlesource.com/chromium/src.git'
     solution = { 'name'   :'src',
                  'url'    : url,
                  'deps_file': '.DEPS.git',
                  'managed'   : False,
                  'custom_deps': {},
                  'safesync_url': '',
     }
-    if props.get('webkit_rev', '') == 'ToT':
-      solution['custom_vars'] = {'webkit_rev': ''}
+    if props.get('webkit_revision', '') == 'ToT':
+      solution['custom_vars'] = {'webkit_revision': ''}
     spec = {
       'solutions': [solution],
     }
     if props.get('target_os'):
       spec['target_os'] = props['target_os'].split(',')
     if props.get('target_os_only'):
       spec['target_os_only'] = props['target_os_only']
     checkout_type = 'gclient_git'
     spec_type = '%s_spec' % checkout_type
     return {
       'type': checkout_type,
       spec_type: spec,
     }
 
   @staticmethod
   def expected_root(_props):
     return 'src'
 
 
 def main(argv=None):
   return Chromium().handle_args(argv)
 
 
 if __name__ == '__main__':
   sys.exit(main(sys.argv))