Set FrameView/OuterViewportContainer size to visible size at minimum scale.

To prevent the inner viewport from becoming larger than the outer viewport
we set the outer viewport's size to be the visible rect at the minimum page
scale.

BUG=364103

Committed: https://src.chromium.org/viewvc/blink?view=rev&revision=173147

Review URL: https://codereview.chromium.org/240863003

git-svn-id: svn://svn.chromium.org/blink/trunk@173352 bbb929c8-8fbe-4397-9dbb-9b2b20218538