Test expectations Win failure on dynamics compressor and analyser.

I do not know why they were failing before (local builds are fine and the initial commit passed all of the bots), but the bots are passing now.

BUG=349523

Review URL: https://codereview.chromium.org/224713003

git-svn-id: svn://svn.chromium.org/blink/trunk@171086 bbb929c8-8fbe-4397-9dbb-9b2b20218538
Add accelerated overflow scroll to bleeding edge fast path

Also converts the accelerated scroll related settings
to be compositing triggers as they should have been
originally.

I've removed some histograms as well. They were meant
to track the percentage of opt-in to composited scrolling,
but since we're no longer investing any effort into the
old, opt-in path, we know there will be no progress, so
these statistics don't seem useful.

BUG=None

Review URL: https://codereview.chromium.org/221283008

git-svn-id: svn://svn.chromium.org/blink/trunk@171087 bbb929c8-8fbe-4397-9dbb-9b2b20218538
HTML Imports: Move HTMLImportLoader ownership to HTMLImportsController

This is a part of refactoring to emphasize HTMLImportLoader
instead of HTMLImport.

By this change, InspectorPage agent is able to traverse loaded
imports wihtout worrying about de-dup.

R=dglazkov@chromium.org,dominicc@chromium.org
TEST=none
BUG=none

Review URL: https://codereview.chromium.org/227973002

git-svn-id: svn://svn.chromium.org/blink/trunk@171088 bbb929c8-8fbe-4397-9dbb-9b2b20218538