Remove LayoutView::doingFullPaintInvalidation()

It was an optimization before slimming paint to shortcut per-object
paint invalidation. Remove it because we do need per-object paint
invalidation.

BUG=600008

Review-Url: https://codereview.chromium.org/2084723002
Cr-Commit-Position: refs/heads/master@{#401697}
11 files changed