Merge recalcStyleForLayoutIgnoringPendingStylesheets into updateLayoutIgnorePendingStylesheets

Now that we don't have partial layout we can recombine these methods. No
one should be calling the other one except updateLayoutIgnorePendingStylesheets
anyway.

R=pdr@chromium.org,ojan@chromium.org

Review URL: https://codereview.chromium.org/209323003

git-svn-id: svn://svn.chromium.org/blink/trunk@169815 bbb929c8-8fbe-4397-9dbb-9b2b20218538