Swarming bots: Add support for perf steps

infra/bots/perf_skia.isolate

Index: infra/bots/perf_skia.isolate
diff --git a/infra/bots/test_skia.isolate b/infra/bots/perf_skia.isolate
similarity index 83%
copy from infra/bots/test_skia.isolate
copy to infra/bots/perf_skia.isolate
index d9eab8cfd9655843f3fb915e1aa362c6885e7f10..420a0d0db819c657a8aaf073eb9428488d7d2e54 100644
--- a/infra/bots/test_skia.isolate
+++ b/infra/bots/perf_skia.isolate
@@ -6,7 +6,7 @@
   ],
   'variables': {
     'command': [
-      'python', 'test_skia.py', '--master_name', '<(MASTER_NAME)', '--builder_name', '<(BUILDER_NAME)', '--build_number', '<(BUILD_NUMBER)', '--slave_name', '<(SLAVE_NAME)', '--revision', '<(REVISION)', '--swarm_out_dir', '${ISOLATED_OUTDIR}',
+      'python', 'perf_skia.py', '--master_name', '<(MASTER_NAME)', '--builder_name', '<(BUILDER_NAME)', '--build_number', '<(BUILD_NUMBER)', '--slave_name', '<(SLAVE_NAME)', '--revision', '<(REVISION)', '--swarm_out_dir', '${ISOLATED_OUTDIR}',

[rmistry, 2016/03/02 14:37:18]

If this is the only difference between the isolate and the script then you
should be able to combine them into a single one to remove duplication.
But if you expect there to be differences in arguments very soon then you should
keep them separate.

[borenet, 2016/03/02 14:42:46]

The fact that they're almost the same is really coincidental.  I'd like them to
be separate.

     ],
   },
 }