Subclass Benchmark Runner script for WebDriver support

Subclass Benchmark Runner script for WebDriver support
https://bugs.webkit.org/show_bug.cgi?id=174390

Patch by Matthew Stewart <matthew_r_stewart@apple.com> on 2017-07-24
Reviewed by Dewei Zhu, Stephanie Lewis.

Add WebServerBenchmarkRunner and WebDriverBenchmarkRunner subclasses.

* Scripts/webkitpy/benchmark_runner/benchmark_builder.py:
(BenchmarkBuilder.__init__):
* Scripts/webkitpy/benchmark_runner/benchmark_runner.py:
(BenchmarkRunner.__init__):
(BenchmarkRunner._find_plan_file):
(BenchmarkRunner._run_one_test.and):
(BenchmarkRunner.execute):
(BenchmarkRunner._get_result): Deleted.
* Scripts/webkitpy/benchmark_runner/run_benchmark.py:
(parse_args):
(start):
* Scripts/webkitpy/benchmark_runner/webdriver_benchmark_runner.py: Added.
(WebDriverBenchmarkRunner):
(WebDriverBenchmarkRunner._get_result):
(WebDriverBenchmarkRunner._run_one_test):
* Scripts/webkitpy/benchmark_runner/webserver_benchmark_runner.py: Added.
(WebServerBenchmarkRunner):
(WebServerBenchmarkRunner.__init__):
(WebServerBenchmarkRunner._get_result):
(WebServerBenchmarkRunner._run_one_test):

git-svn-id: https://svn.webkit.org/repository/webkit/trunk@219857 268f45cc-cd09-0410-ab3c-d52691b4dbfc