Introduce a SVGUnknownElement class for unknown SVG elements

Introduce a SVGUnknownElement class for unknown SVG elements

Introduce a SVGUnknownElement class and have it override rendererIsNeeded()
to return false. We now use SVGUnknownElement type (instead of SVGElement)
for unknown SVG elements. As a consequence, SVGElement::rendererIsNeeded()
no longer needs to return false and can finally behave as
SVGStyledElement::rendererIsNeeded() used to behave.

R=pdr
BUG=231536
Committed: https://src.chromium.org/viewvc/blink?view=rev&revision=155426

[pdr., 2013-08-01 21:05:02]

On 2013/08/01 08:15:06, Christophe Dumez wrote:

LGTM.

One nit: can you add a comment in SVGUnknownElement that describes the two cases
this is used (custom elements and non-SVG tags in SVG)? I think this will remind
us later when we revisit this code a year from now.

[commit-bot: I haz the power, 2013-08-02 06:38:54]

CQ is trying da patch. Follow status at
https://chromium-status.appspot.com/cq/ch.dumez@sisa.samsung.com/21498002/6001

[commit-bot: I haz the power, 2013-08-02 09:45:48]

Change committed as 155426