Remove unused method and de-virtualize others in Element.h

Remove unused method and de-virtualize others in Element.h

The de-virtualization possibilities were noted whilst "FINALizing" the Node
hierarchy. If a method is successfully marked FINAL but then fails when marked
OVERRIDE as well, the method by definition does not need to be virtual.

R=esprehn@chromium.org
TEST=wktry

Committed: https://src.chromium.org/viewvc/blink?view=rev&revision=149493

[Chris Evans, 2013-04-30 23:27:13]

Split out from FINALizing CL, as discussed earlier.

[esprehn, 2013-04-30 23:39:46]

LGTM.

[jamesr, 2013-04-30 23:42:07]

Why doesn't FINAL imply OVERRIDE?

[esprehn, 2013-05-01 00:12:18]

On 2013/04/30 23:42:07, jamesr wrote:
> Why doesn't FINAL imply OVERRIDE?

That's a really good question!

[Chris Evans, 2013-05-01 00:25:38]

Committed patchset #1 manually as r149493 (presubmit successful).

[Chris Evans, 2013-05-01 00:54:34]

On 2013/05/01 00:12:18, esprehn wrote:
> On 2013/04/30 23:42:07, jamesr wrote:
> > Why doesn't FINAL imply OVERRIDE?
> 
> That's a really good question!

I agree! Perhaps it's compiler-specific, but clang for sure doesn't imply
override when it has final.
(This of course refers to method annotations; override is not a supported
keyword on class-wide annotations.)

Since FINAL and OVERRIDE are macros, I could introduce FINAL_METHOD macro (which
is just "override final" on compilers with support) and do a mass search/replace
if you think there's value?