The pyauto-based V8 benchmark test in perf.py now runs iteratively.
The pyauto-based V8 benchmark test in perf.py now runs iteratively.

Previously, pyauto perf test perf.BenchmarkPerfTest.testV8BenchmarkSuite
ran the V8 benchmarks just once, then outputted the results.  However, it
turns out the results sometimes vary considerably from run to run, even
on the same build.  The test now runs iteratively and outputs the average
results from all iterations, to help reduce this noise.

BUG=None
TEST=None

Review URL: http://codereview.chromium.org/8351081

git-svn-id: de016e52bd170d2d4f2344f9bf92d50478b649e0@108534 0039d316-1c4b-4281-b951-d872f2087c98

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