[SVG] Promote PathOpsSVGClipping to experimental.

[SVG] Promote PathOpsSVGClipping to experimental.

Re-enabling pathops-based SVG clipping after numerous Skia updates.

A handful of pixel tests require minor rebaselines.

BUG=263911
R=fs@opera.com, schenney@chromium.org, pdr@chromium.org

Committed: https://src.chromium.org/viewvc/blink?view=rev&revision=177411

[f(malita), 2014-07-02 14:24:48]

Layout test diffs can be inspected here:
https://storage.googleapis.com/chromium-layout-test-archives/linux_blink_rel/...

[fs, 2014-07-02 14:41:57]

LGTM (not platform-owner)

[Stephen Chennney, 2014-07-02 16:33:48]

lgtm

[commit-bot: I haz the power, 2014-07-02 16:34:13]

CQ is trying da patch. Follow status at
 https://chromium-status.appspot.com/cq/fmalita@chromium.org/362333002/40001

[commit-bot: I haz the power, 2014-07-02 17:43:22]

FYI, CQ is re-trying this CL (attempt #1).
The failing builders are:
  win_blink_rel on tryserver.blink
(http://build.chromium.org/p/tryserver.blink/builders/win_blink_rel/builds/15106)

[commit-bot: I haz the power, 2014-07-02 18:25:59]

The CQ bit was unchecked by commit-bot@chromium.org

[commit-bot: I haz the power, 2014-07-02 18:26:01]

Try jobs failed on following builders:
  win_blink_rel on tryserver.blink
(http://build.chromium.org/p/tryserver.blink/builders/win_blink_rel/builds/15116)

[f(malita), 2014-07-02 19:00:30]

Committed patchset #3 manually as r177411 (presubmit successful).