De-virtualize RenderText::computePreferredLogicalWidths()

There are no overrides.

Also included in the CL:

* drop unused textBoxDataMap param from placeBoxesInInlineDirection() &
  placeBoxRangeInInlineDirection()
* add GlyphOverflow::isZero() to reduce boilerplate checks.

R=jbroman@chromium.org,leviw@chromium.org,eae@chromium.org

Review URL: https://codereview.chromium.org/416623002

git-svn-id: svn://svn.chromium.org/blink/trunk@178807 bbb929c8-8fbe-4397-9dbb-9b2b20218538