Incrementally invalidate boxes with borders if possible

This actually restores RenderBox::incrementallyInvalidatePaint()
which was removed in http://src.chromium.org/viewvc/blink?view=revision&revision=177971
because it was buggy.

This change handles borders and border-radius.

BUG=390587

Review URL: https://codereview.chromium.org/399173005

git-svn-id: svn://svn.chromium.org/blink/trunk@180596 bbb929c8-8fbe-4397-9dbb-9b2b20218538
DevTools: Resource Timing: update labels.

BUG=403508

Review URL: https://codereview.chromium.org/486623003

git-svn-id: svn://svn.chromium.org/blink/trunk@180597 bbb929c8-8fbe-4397-9dbb-9b2b20218538
Clip path shouldn't cause constant repaints

During style recalc, we were comparing the old and new clip path by pointer,
which meant we'd think we had a new clip path whenever we malloced up a new
clip path object. However, we don't need to trigger a repaint if the contents
of the path are the same as before.

R=eseidel@chromium.org
BUG=378948

Review URL: https://codereview.chromium.org/469943004

git-svn-id: svn://svn.chromium.org/blink/trunk@180598 bbb929c8-8fbe-4397-9dbb-9b2b20218538
[Cleanup] Removing dead code in multiprocessing_bootstrap.py

Removing gtk related code in multiprocessing_bootstrap.py

Review URL: https://codereview.chromium.org/483143003

git-svn-id: svn://svn.chromium.org/blink/trunk@180599 bbb929c8-8fbe-4397-9dbb-9b2b20218538