Don't rely on values computed as a side effect of paint.

Contrary to the assertions on the bug, the current code is correct. As
the user changes the selection, there will naturally be a visual
affordance to indicate the selection changes. By the time we scroll,
RL::hasBlockSelectionGapsBounds will be current and correct.

That said, the hope is that in the future paint will have no side
effects at all, nor do we want layout tests to require repaints during
their execution. So even if this is technically correct it's undesirable
on a number of levels.

This cl replaces the use of hasBlockSelectionGapsBounds with non-paint
related code (in fact, that function could be removed entirely).

R=abarth@chromium.org
BUG=353827

Review URL: https://codereview.chromium.org/208203002

git-svn-id: svn://svn.chromium.org/blink/trunk@169752 bbb929c8-8fbe-4397-9dbb-9b2b20218538
NavigationAction should not retain Event.

NavigationAction class before this patch had a RefPtr<Event> as its member. The event retained the previous document longer than necessary, resulting in a soft leak. This patch removes the member from the NavigationAction class and replaces it with DOMTimeStamp of the event which is the only information may be retrieved afterward.

BUG=None

Review URL: https://codereview.chromium.org/206453010

git-svn-id: svn://svn.chromium.org/blink/trunk@169753 bbb929c8-8fbe-4397-9dbb-9b2b20218538