[test] Isolate files the perf runner depends on

BUG=chromium:616879
NOTRY=true
TBR=mtrofin@chromium.org

Review-Url: https://codereview.chromium.org/2476273003
Cr-Commit-Position: refs/heads/master@{#40821}

test/perf.isolate

@@ -8,6 +8,11 @@
     ],
     'files': [
       '../tools/run_perf.py',
+      # TODO(machenbach): These files are referenced by the perf runner.
+      # They should be transformed into a proper python module.
+      '../tools/testrunner/local/commands.py',
+      '../tools/testrunner/local/utils.py',
+      '../tools/testrunner/objects/output.py',
       # This is often used to trigger performance bots. We include it in the
       # isolate to not get these builds deduped.
       '../tools/whitespace.txt',