Fixed scrollFocusedNodeIntoRect to also scroll pinch viewport.

scrollFocusedNodeIntoRect now modifies the given rect so that it's only as big as
the rect visible to the user. It also will scroll the pinch viewport so the method
works while the user is pinched-in or the On-screen-keyboard is up.

Also removed scrollFocusedNodeIntoView which had no callers.

BUG=370592

Review URL: https://codereview.chromium.org/269323002

git-svn-id: svn://svn.chromium.org/blink/trunk@173772 bbb929c8-8fbe-4397-9dbb-9b2b20218538