Remove the CSS_COMPOSITING define, the CSS blending and compositing

Remove the CSS_COMPOSITING define, the CSS blending and compositing
implementation is currently under a runtime guard.

BUG: 229926

[eseidel, 2013-04-16 21:48:52]

Isn't this detectable from the Web?

[ojan, 2013-04-17 00:03:53]

On 2013/04/16 21:48:52, Eric Seidel (Google) wrote:
> Isn't this detectable from the Web?

FWIW, I filed https://code.google.com/p/chromium/issues/detail?id=232181 about
this.

[eseidel, 2013-04-17 00:20:05]

To answer my own question: yes this is detectable from the web.  We need to
provide a way to have runtime-enabled CSS properties and values.  This property
is going to have to keep it's prefix or compile-time define until then. :(

[jamesr, 2013-04-17 00:52:00]

On 2013/04/17 00:20:05, Eric Seidel (Google) wrote:
> To answer my own question: yes this is detectable from the web.  We need to
> provide a way to have runtime-enabled CSS properties and values.  This
property
> is going to have to keep it's prefix or compile-time define until then. :(

D'oh, I thought that this was properly runtime-guarded but apparently it isn't. 
The define was flipped recently.  I'll revert the compile flip until this can be
properly runtime guarded.

[eseidel, 2013-04-17 01:40:18]

It's currently impossible to guard CSS properties at runtime.  It's possible to
guard CSS values if done carefully.