Simplify SVG's styleDidChange

This is a merge of wkbug.com/123108 by Andreas Kling <akling@apple.com>.

SVG's styleWillChange code can me moved into styleDidChange which both
simplifies this code and removes a few virtuals. This patch also merges
RenderSVGBlock::styleWillChange into RenderSVGBlock::styleDidChange
which was not in the WebKit patch.

No new tests, covered by existing tests.

Review URL: https://codereview.chromium.org/32343009

git-svn-id: svn://svn.chromium.org/blink/trunk@160259 bbb929c8-8fbe-4397-9dbb-9b2b20218538
Added run-perf-test.cfg and PRESUBMIT.py. The bisect/perf bots work by modifying a .cfg file with the parameters of the job (ie. revision, command, repetitions, etc...) and submitting that as a patch to the bot. Since a single patch can't span both blink and chromium, we need a run-perf-test.cfg in each depot that we're likely to try running perf tests from.

Waiting on: https://codereview.chromium.org/27165006/
Needs Follow up: https://codereview.chromium.org/34723005

BUG=
TEST=

Using the config:

config = {
  'command': 'tools/perf/run_measurement -v --browser=release blink_perf third_party/WebKit/PerformanceTests/Layout/floats_50_100.html',
  'metric': 'floats_50_100/floats_50_100',
  'repeat_count': '1',
  'max_time_minutes': '20',
  'truncate_percent': '25',
}

Submit a try job via "git try -b linux_perf_bisect".

Review URL: https://codereview.chromium.org/33553003

git-svn-id: svn://svn.chromium.org/blink/trunk@160260 bbb929c8-8fbe-4397-9dbb-9b2b20218538