Encapsulate FloatingObject's constructor inside create
https://bugs.webkit.org/show_bug.cgi?id=110169

Reviewed by Darin Adler.

Added FloatingObject::create and made FloatingObject's constructor private.
Also added RenderBlock::ensureFloatingObjects to help lazily creating FloatingObjects.

* rendering/RenderBlock.cpp:
(WebCore::RenderBlock::insertFloatingObject):
(WebCore::RenderBlock::addOverhangingFloats):
(WebCore::RenderBlock::addIntrudingFloats):
(WebCore::RenderBlock::ensureFloatingObjects):
(WebCore::RenderBlock::FloatingObjects::create):
(WebCore::RenderBlock::FloatingObjects::FloatingObjects):
* rendering/RenderBlock.h:
(FloatingObjects):
(RenderBlock):


git-svn-id: http://svn.webkit.org/repository/webkit/trunk@143289 268f45cc-cd09-0410-ab3c-d52691b4dbfc