[test] Add arm perf trybot to runner script.

tools/try_perf.py

 #!/usr/bin/env python
 # Copyright 2014 the V8 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.
 
 import argparse
 import find_depot_tools
 import sys
 
 find_depot_tools.add_depot_tools_to_path()
 
 from git_cl import Changelist
 
 BOTS = {
+  '--arm32': 'v8_arm32_perf_try',
   '--linux32': 'v8_linux32_perf_try',
   '--linux64': 'v8_linux64_perf_try',
   '--linux64_haswell': 'v8_linux64_haswell_perf_try',
 }
 
 DEFAULT_BOTS = [
   'v8_linux32_perf_try',
   'v8_linux64_haswell_perf_try',
 ]
 
@@ skipping 30 matching lines @@
   masters = {
     'internal.client.v8': dict((b, options.benchmarks) for b in options.bots),
   }
   cl.RpcServer().trigger_distributed_try_jobs(
       cl.GetIssue(), cl.GetMostRecentPatchset(), cl.GetBranch(),
       False, None, masters)
   return 0
 
 if __name__ == "__main__":  # pragma: no cover
   sys.exit(main())