Add toSVGColor|Paint() to cleanup static_cast<>, and use it

Add toSVGColor|Paint() to cleanup static_cast<>, and use it

SVGColor and SVGPaint can't use DEFINE_CSS_VALUE_TYPE_CASTS(), this cl adds
toSVGColor() and toSVGPaint() manually. Those functions will help to detect
bad type cast.

BUG=N/A

Committed: https://src.chromium.org/viewvc/blink?view=rev&revision=159425

[gyuyoung-inactive, 2013-10-10 11:21:29]

Add tkent.

[Stephen Chennney, 2013-10-10 15:21:19]

On 2013/10/10 11:21:29, gyuyoung wrote:
> Add tkent.

Run this through the trybots please. And create a bug to reference.

[tkent, 2013-10-10 21:00:07]

lgtm for !Source/bindings/

[haraken, 2013-10-10 23:42:52]

On 2013/10/10 21:00:07, tkent wrote:
> lgtm for !Source/bindings/

LGTM for bindings/

[commit-bot: I haz the power, 2013-10-10 23:46:08]

CQ is trying da patch. Follow status at
https://chromium-status.appspot.com/cq/gyuyoung.kim@samsung.com/26261009/1

[gyuyoung-inactive, 2013-10-11 00:41:08]

On 2013/10/10 21:00:07, tkent wrote:
> lgtm for !Source/bindings/

Sorry, I missed to cleanup static_cast<const SVGColor|Paint*>. So, I update this
patch.

[commit-bot: I haz the power, 2013-10-11 01:05:41]

CQ is trying da patch. Follow status at
https://chromium-status.appspot.com/cq/gyuyoung.kim@samsung.com/26261009/14001

[commit-bot: I haz the power, 2013-10-11 05:29:59]

Change committed as 159425