Make FloatingObjects own it's FloatingObject instances

Make FloatingObjects own it's FloatingObject instances
https://bugs.webkit.org/show_bug.cgi?id=121323

Reviewed by Alexandru Chiculita.

As part of decoupling FloatingObjects from RenderBlock, change
FloatingObjects to properly manage the FloatingObject instances it
contains.

No new tests, no behavior change.

* rendering/FloatingObjects.cpp:
(WebCore::FloatingObject::FloatingObject): Make the constructors
private so that FloatingObjects can only be created with an OwnPtr.
Also make a RenderBox required to create a FloatingObject.
(WebCore::FloatingObject::create): Factory method to create a vanilla
FloatingObject.
(WebCore::FloatingObject::copyToNewContainer): Factory method to copy
an existing FloatingObject in the case it is overhanging or intruding
and needs to be copied to the block that it overhangs or intrudes
into.
(WebCore::FloatingObject::unsafeClone): Rename this method so it is
more obvious that it really shouldn't be used, and to make it more
obvious that one should use the copyToNewContainer method for all
normal FloatingObject copies.
(WebCore::FloatingObjects::clear): Delete all the FloatingObjects in
the set before clearing it.
(WebCore::FloatingObjects::moveAllToFloatInfoMap): Move all of the
FloatingObjects in the set to a RendererToFloatInfoMap. This is used
in RenderBlockFlow::clearFloats to when it is readding floats after
clearing the set.
(WebCore::FloatingObjects::add): Take an OwnPtr.
(WebCore::FloatingObjects::remove): Delete the removed FloatingObject.
* rendering/FloatingObjects.h: Remove FloatingObject::setRenderer(),
since the RenderBox must be set in the constructor.
* rendering/RenderBlock.cpp:
(WebCore::RenderBlock::moveAllChildrenIncludingFloatsTo): Rename clone
to unsafeClone.
(WebCore::RenderBlock::removeFloatingObjects): Don't delete anymore,
since clear does it.
(WebCore::RenderBlock::insertFloatingObject): Handle OwnPtr properly.
(WebCore::RenderBlock::removeFloatingObject): Don't delete anymore,
since remove does it.
(WebCore::RenderBlock::removeFloatingObjectsBelow): Ditto.
(WebCore::RenderBlock::addOverhangingFloats): Use copyToNewContainer
and OwnPtr.
(WebCore::RenderBlock::addIntrudingFloats): Ditto.
* rendering/RenderBlockFlow.cpp:
(WebCore::RenderBlockFlow::clearFloats): Use exportToFloatInfoMap.

git-svn-id: https://svn.webkit.org/repository/webkit/trunk@155906 268f45cc-cd09-0410-ab3c-d52691b4dbfc