Add isHTMLPlugInElement() helpers for consistency with other HTML elements

Add isHTMLPlugInElement() helpers for consistency with other HTML elements

Add isHTMLPlugInElement() helpers for consistency with other HTML elements.
Those helpers rely on the isPluginElement() virtual function to check if
an Element is an HTMLPlugInElement.

R=tkent, adamk
BUG=346095
Committed: https://src.chromium.org/viewvc/blink?view=rev&revision=169589

[Inactive, 2014-03-18 21:01:26]

I rebased the patch due to https://codereview.chromium.org/202813005/

[eseidel, 2014-03-18 21:22:21]

It's always a bit lame when superclasses need to know all of their subclasses. 
I think in this case it doesn't matter much either way, since I think it's
unlikely we'll ever add another plugin element subclass.

[Inactive, 2014-03-18 21:59:55]

On 2014/03/18 21:22:21, eseidel wrote:
> It's always a bit lame when superclasses need to know all of their subclasses.

> I think in this case it doesn't matter much either way, since I think it's
> unlikely we'll ever add another plugin element subclass.

Yes, I understand. I don't have strong feelings either way but I think we should
be consistent one way or another.

HTMLMediaElement and HTMLFrameElementBase were updated recently (by Philip and
me) to rely on the tag names of their subclasses. So this CL is a follow-up to
this work.
But really, if we want to keep the virtual methods for HTMLElements, I don't
really mind making it consistent the other way.

[tkent, 2014-03-19 01:04:27]

I think no one blames if we just add WebCore::isHTMLPluginElement without
removing Element::isPluginElement.

[Inactive, 2014-03-19 15:08:23]

On 2014/03/19 01:04:27, tkent wrote:
> I think no one blames if we just add WebCore::isHTMLPluginElement without
> removing Element::isPluginElement.

Ok, I did that. Please take another look.
Since the virtual method is called isPluginElement() and not
isHTMLPlugInElement(), there is no naming conflict.

[tkent, 2014-03-19 22:50:03]

lgtm

[commit-bot: I haz the power, 2014-03-19 22:50:07]

CQ is trying da patch. Follow status at
https://chromium-status.appspot.com/cq/ch.dumez@samsung.com/202153005/40001

[commit-bot: I haz the power, 2014-03-19 23:00:17]

Change committed as 169589