Source/WebCore: Issues with merging ruby bases.

Source/WebCore: Issues with merging ruby bases.
https://bugs.webkit.org/show_bug.cgi?id=67240

Reviewed by James Robinson.

1) Change fromBeforeChild to beforeChild to match
webkit rendering naming conventions.
2) Add assert to verify ruby base is indeed emptied
after collecting all children in a single base.
3) Fix condition in mergeBlockChildren to bail out only
when we have no children and there is no work to merge
children to toBase.

Test: fast/ruby/ruby-overhang-crash.html

* rendering/RenderRubyBase.cpp:
(WebCore::RenderRubyBase::moveChildren):
(WebCore::RenderRubyBase::moveInlineChildren):
(WebCore::RenderRubyBase::moveBlockChildren):
(WebCore::RenderRubyBase::mergeBlockChildren):
* rendering/RenderRubyBase.h:
* rendering/RenderRubyRun.cpp:
(WebCore::RenderRubyRun::removeChild):

LayoutTests: Issues with merging ruby bases.
https://bugs.webkit.org/show_bug.cgi?id=67240

Reviewed by James Robinson.

ASSERTION FAILED: !needsLayout() in RenderRubyRun::getOverhang.

* fast/ruby/ruby-overhang-crash-expected.txt: Added.
* fast/ruby/ruby-overhang-crash.html: Added.

git-svn-id: http://svn.webkit.org/repository/webkit/trunk@95462 268f45cc-cd09-0410-ab3c-d52691b4dbfc