Remove assert from FrameView::resumeOverflowEvents

This assert shows we don't pair the suspend and resume calls properly.
We're going to remove this entire system soon so just comment out the
assert for now.

BUG=299788
R=pdr@chromium.org
TBR=pdr@chromium.org

Review URL: https://codereview.chromium.org/25406002

git-svn-id: svn://svn.chromium.org/blink/trunk@158562 bbb929c8-8fbe-4397-9dbb-9b2b20218538