Document.body should check interface type and be nullable

Document.body should check interface type and be nullable

SPEC: http://www.whatwg.org/specs/web-apps/current-work/multipage/dom.html#document

This CL enabled an interface type checking on setter of Document.body
and a nullable type to body attribute as per specification.

In addition, with this change, a failed test case will be passed in
http://w3c-test.org/html/dom/documents/dom-tree-accessors/document.body-setter-01.html

TEST=LayoutTests/fast/dom/setter-type-enforcement.html

Behavior in other browsers:
*)FF: PASS
*)IE: FAIL

Committed: https://src.chromium.org/viewvc/blink?view=rev&revision=178039

[kangil_, 2014-07-14 07:31:32]

PTAL

[haraken, 2014-07-14 07:44:12]

Can we remove some code from Document.cpp that had been used to throw the
HierarchyRequestError when the body was null?

[kangil_, 2014-07-14 08:04:43]

On 2014/07/14 07:44:12, haraken wrote:
> Can we remove some code from Document.cpp that had been used to throw the
> HierarchyRequestError when the body was null?

Seems still valid code lines are in Document::setBody() according to algorithm 1
in spec.
'If the new value is not a body or frameset element, then throw a
HierarchyRequestError exception and abort these steps.'

[haraken, 2014-07-14 08:10:24]

On 2014/07/14 08:04:43, kangil_ wrote:
> On 2014/07/14 07:44:12, haraken wrote:
> > Can we remove some code from Document.cpp that had been used to throw the
> > HierarchyRequestError when the body was null?
> 
> Seems still valid code lines are in Document::setBody() according to algorithm
1
> in spec.
> 'If the new value is not a body or frameset element, then throw a
> HierarchyRequestError exception and abort these steps.'

Makes sense, thanks for the clarification.

LGTM.

[kangil_, 2014-07-14 08:15:24]

The CQ bit was checked by kangil.han@samsung.com

[commit-bot: I haz the power, 2014-07-14 08:16:33]

CQ is trying da patch. Follow status at
 https://chromium-status.appspot.com/cq/kangil.han@samsung.com/392523002/1

[commit-bot: I haz the power, 2014-07-14 09:22:13]

Change committed as 178039