RenderBlockFlow should only expose its line boxes as RootInlineBox.
<https://webkit.org/b/123878>
The line boxes attached directly to a RenderBlockFlow are always
RootInlineBox objects, so call sites should always use the tightly
typed firstRootBox() and lastRootBox().
This allows the compiler to devirtualize calls to member functions
of RootInlineBox that are marked FINAL.
Reviewed by Antti Koivisto.
git-svn-id: http://svn.webkit.org/repository/webkit/trunk@158730 268f45cc-cd09-0410-ab3c-d52691b4dbfc
7 files changed
