Roll script: Update after SVN support was dropped from depot tools

tools/autoroller/roll_chromium_revision.py

 #!/usr/bin/env python
 # Copyright (c) 2015 The WebRTC project authors. All Rights Reserved.
 #
 # Use of this source code is governed by a BSD-style license
 # that can be found in the LICENSE file in the root of the source
 # tree. An additional intellectual property rights grant can be found
 # in the file PATENTS.  All contributing project authors may
 # be found in the AUTHORS file in the root of the source tree.
 
 """Script to roll chromium_revision in the WebRTC DEPS file."""
@@ skipping 38 matching lines @@
                                     'path url current_rev new_rev')
 
 class RollError(Exception):
   pass
 
 
 def ParseDepsDict(deps_content):
   local_scope = {}
   var = GClientKeywords.VarImpl({}, local_scope)
   global_scope = {
-    'File': GClientKeywords.FileImpl,
     'From': GClientKeywords.FromImpl,
     'Var': var.Lookup,
     'deps_os': {},
   }
   exec(deps_content, global_scope, local_scope)
   return local_scope
 
 
 def ParseLocalDepsFile(filename):
   with open(filename, 'rb') as f:
@@ skipping 367 matching lines @@
   _CreateRollBranch(opts.dry_run)
   UpdateDeps(deps_filename, current_cr_rev, new_cr_rev)
   _LocalCommit(commit_msg, opts.dry_run)
   _UploadCL(opts.dry_run, opts.rietveld_email)
   _SendToCQ(opts.dry_run, opts.skip_cq)
   return 0
 
 
 if __name__ == '__main__':
   sys.exit(main())