Currently Blink creates a fake run for a given isolated span during each call
to createBidiRunsForLine. However in some cases the added fake run is not necessary.

This patch uses the same logic in RenderBlockFlow::appendRunsObject to create
fake runs just when they are really needed.

Committed: https://src.chromium.org/viewvc/blink?view=rev&revision=160495

Review URL: https://codereview.chromium.org/39783004

git-svn-id: svn://svn.chromium.org/blink/trunk@161410 bbb929c8-8fbe-4397-9dbb-9b2b20218538