Throttle JavaScript timers in prerender tabs.

For energy usage, invisible tabs should have a lower timer threshold.
Based on file history, it looks like prerender was not considered when this logic was introduced.

BUG=400343

Review URL: https://codereview.chromium.org/431503005

git-svn-id: svn://svn.chromium.org/blink/trunk@179618 bbb929c8-8fbe-4397-9dbb-9b2b20218538
[DevTools] Make inspector-protocol tests work with messages passed as objects.

This mirrors the real inspector frontend logic,
where we already get objects instead of strings.

BUG=none

Review URL: https://codereview.chromium.org/444883004

git-svn-id: svn://svn.chromium.org/blink/trunk@179619 bbb929c8-8fbe-4397-9dbb-9b2b20218538
Make Screen Orientation us Platform Events in order to handle polling.

BUG=162827
NOTRY=True

Review URL: https://codereview.chromium.org/419643008

git-svn-id: svn://svn.chromium.org/blink/trunk@179620 bbb929c8-8fbe-4397-9dbb-9b2b20218538