Use toSVGMarkerElement() instead of static_cast<>

Use toSVGMarkerElement() instead of static_cast<>

Though there is toSVGMarkerElement(), some files still use static_cast<SVGMarkerElement*>.
To remove all static_cast<> use, we need to change argument from SVGElement to Node.

BUG=

Committed: https://src.chromium.org/viewvc/blink?view=rev&revision=154461

[gyuyoung-inactive, 2013-07-16 09:29:58]

Add tkent as reviewer.

[Stephen Chennney, 2013-07-16 17:27:59]

lgtm

[commit-bot: I haz the power, 2013-07-16 17:28:27]

CQ is trying da patch. Follow status at
https://chromium-status.appspot.com/cq/gyuyoung.kim@samsung.com/19351003/1001

[commit-bot: I haz the power, 2013-07-16 20:13:02]

Retried try job too often on linux_layout_rel for step(s) webkit_tests
http://build.chromium.org/p/tryserver.chromium/buildstatus?builder=linux_layo...

[pdr., 2013-07-16 23:32:41]

@gyuyoung, I'm worried that we're heading in the wrong direction by continuing
to land these patches.

Do you mind responding to my comment in
https://codereview.chromium.org/18278003/#msg14 ?

[tkent, 2013-07-16 23:37:04]

On 2013/07/16 23:32:41, pdr wrote:
> @gyuyoung, I'm worried that we're heading in the wrong direction by continuing
> to land these patches.
> 
> Do you mind responding to my comment in
> https://codereview.chromium.org/18278003/#msg14 ?

pdr, using toFooElement is welcome though isFooElement has downside.

[pdr., 2013-07-16 23:39:51]

On 2013/07/16 23:37:04, tkent wrote:
> On 2013/07/16 23:32:41, pdr wrote:
> > @gyuyoung, I'm worried that we're heading in the wrong direction by
continuing
> > to land these patches.
> > 
> > Do you mind responding to my comment in
> > https://codereview.chromium.org/18278003/#msg14 ?
> 
> pdr, using toFooElement is welcome though isFooElement has downside.

So true! Sorry about the noise, I just mis-read this patch.

Please continue with toSVG* changes :)

[gyuyoung-inactive, 2013-07-17 01:24:06]

On 2013/07/16 23:39:51, pdr wrote:
> On 2013/07/16 23:37:04, tkent wrote:
> > On 2013/07/16 23:32:41, pdr wrote:
> > > @gyuyoung, I'm worried that we're heading in the wrong direction by
> continuing
> > > to land these patches.
> > > 
> > > Do you mind responding to my comment in
> > > https://codereview.chromium.org/18278003/#msg14 ?
> > 
> > pdr, using toFooElement is welcome though isFooElement has downside.
> 
> So true! Sorry about the noise, I just mis-read this patch.
> 
> Please continue with toSVG* changes :)

@pdr, I reply your comment at there.

[commit-bot: I haz the power, 2013-07-18 02:21:33]

CQ is trying da patch. Follow status at
https://chromium-status.appspot.com/cq/gyuyoung.kim@samsung.com/19351003/21001

[commit-bot: I haz the power, 2013-07-18 03:15:33]

Change committed as 154461