Move m_floatingObjects to RenderBlockFlow from RenderBlock

Floats are part of block flow, not every RenderBlock can contain
floats. This change makes it so that RenderBlock no longer can contain
floats, only RenderBlockFlow can.

This also moves a bunch of line layout stuff over to RenderBlockFlow,
but makes no effort to move all of line layout, as all of that is
destined to move in future refactorings.

Review URL: https://codereview.chromium.org/27518011

git-svn-id: svn://svn.chromium.org/blink/trunk@160292 bbb929c8-8fbe-4397-9dbb-9b2b20218538
Remove unnecessary .get() in arguments of toClassName functions.
Also, apply DEFINE_NODE_TYPE_CASTS to HTMLHtmlElement and HTMLTitleElement.

BUG=309516
TEST=none; no behavior changes.

Review URL: https://codereview.chromium.org/34613012

git-svn-id: svn://svn.chromium.org/blink/trunk@160293 bbb929c8-8fbe-4397-9dbb-9b2b20218538
IDL compiler: [Custom(Setter), Replaceable]

Next (and final) part.

Custom setters on replaceable attributes are an obnoxious special case,
especially because:
* They result in a setter callback being generated, but not the setter.
This means we have to have two separate checks in the template:
one for the setter, one for the setter callback.

This occurs for 2 attributes in Window.idl:
[Custom, Replaceable] readonly attribute Event event;
[CustomSetter, Replaceable] readonly attribute Window opener;

BUG=239771
NOTRY=true

Review URL: https://codereview.chromium.org/35123002

git-svn-id: svn://svn.chromium.org/blink/trunk@160294 bbb929c8-8fbe-4397-9dbb-9b2b20218538