Make STRING_STATS track StringImpl overhead

This CL improve STRING_STATS to report the amount of memory spent on StringImpl
overhead. The amount of overhead due to StringImpl is simply the number of
strings times the sizeof(StringImpl), but including it in the stats saves a
bunch of calculation.

Also, this CL fixes a few STRING_STATS bugs that have crept in due to my recent
String refactorings.

R=eseidel
BUG=262320

Review URL: https://chromiumcodereview.appspot.com/19466006

git-svn-id: svn://svn.chromium.org/blink/trunk@154663 bbb929c8-8fbe-4397-9dbb-9b2b20218538
Fix usage of prefixed CSS transitions in Blink.

We're asking our users to move to unprefixed CSS properties but
we don't do it ourselves :D. Let's fix the few places where we
create CSS transitions to use the unprefixed enum value.

Review URL: https://chromiumcodereview.appspot.com/19970002

git-svn-id: svn://svn.chromium.org/blink/trunk@154664 bbb929c8-8fbe-4397-9dbb-9b2b20218538
Use OwnPtr for SCRIPT_FONTPROPERTIES.

Make the ownership of SCRIPT_FONTPROPERTIES in FontPlatformDataChromiumWin explicit using an OwnPtr.

BUG=

Review URL: https://chromiumcodereview.appspot.com/19520009

git-svn-id: svn://svn.chromium.org/blink/trunk@154665 bbb929c8-8fbe-4397-9dbb-9b2b20218538
Remove flaky expectation for fast/events/touch/send-oncancel-event.html

It consistently passed for a while now

BUG=261278

Review URL: https://chromiumcodereview.appspot.com/19698003

git-svn-id: svn://svn.chromium.org/blink/trunk@154666 bbb929c8-8fbe-4397-9dbb-9b2b20218538
Suppress more media timeupdate events when seeking

Playback progress timer firing should not cause timeupdate event
scheduling while seeking, and neither should active text track cue
updating cause timeupdate event scheduling while seeking.
Timeupdate event is scheduled during finishSeek for these scenarios.

BUG=261722
R=acolwell@chromium.org,adamk@chromium.org
TEST=no media layout test regression on linux, video-seek-to-[duration,middle] pass on Chrome for Android

Review URL: https://chromiumcodereview.appspot.com/19842005

git-svn-id: svn://svn.chromium.org/blink/trunk@154667 bbb929c8-8fbe-4397-9dbb-9b2b20218538