Remove unneccessary time.h include from CurrentTime.h

Review URL: https://chromiumcodereview.appspot.com/22912024

git-svn-id: svn://svn.chromium.org/blink/trunk@156724 bbb929c8-8fbe-4397-9dbb-9b2b20218538
Add layout tests for universal overflow scrolling

This cl adds layout tests that stress the corner cases that the old composited
scrolling path could not handle. Namely, situations where promoting would cause
stacking and clipping errors.

This is blink-side patch 1 of https://docs.google.com/a/chromium.org/document/d/1Ln57_v6_4RmuuvtWnpsfBOUeDFrPsYNFW13dwuQ8UD8.

BUG=254435

Review URL: https://chromiumcodereview.appspot.com/22620002

git-svn-id: svn://svn.chromium.org/blink/trunk@156725 bbb929c8-8fbe-4397-9dbb-9b2b20218538
Make hasRareData check an ASSERT_WITH_SECURITY_IMPLICATION

Given that the next thing done after checking hasRareData() is to access
the rare data as if it existed, this check failing likely means either
a use-after-free or accessing the render tree as NodeRareData.

R=inferno@chromium.org

Review URL: https://chromiumcodereview.appspot.com/23451002

git-svn-id: svn://svn.chromium.org/blink/trunk@156726 bbb929c8-8fbe-4397-9dbb-9b2b20218538