[CSS Blending] When applying mix-blend-mode on an element,

[CSS Blending] When applying mix-blend-mode on an element,
its contents and its children should blend as a whole with the
backdrop.

BUG=229615
Committed: https://src.chromium.org/viewvc/blink?view=rev&revision=164026

[mitica, 2013-12-09 12:16:48]

Hi Stephen, please review this change.
Thanks!

[mitica, 2013-12-09 13:46:30]

The first approach wasn't right, I'm working on a proper solution

[mitica, 2013-12-10 14:51:18]

For a group of elements like
<div class="A">
	<div class="B" style="mix-blend-mode: multiply">
		<div class="C">

the current implementation behaves as follows: C would blend with B and this
result would then blend with A.
This behaviour is incorrect. Instead, B and C should blend as a whole with the
contents of A.

The initial fix broke background blending, the second one addresses this issue
in the following way:
GraphicContext can have a blendMode applied either from having background blend
mode (achieved by setting the background-blend-mode property) or by having
mix-blend-mode set.
If none of these properties is detected, the context has blending set from a
parent element, which would result in the incorrect behaviour described above.
The fix is to reset the blend mode back to WebBlendModeNormal.

[mitica, 2013-12-12 09:54:58]

I've found a much simpler and better solution, please excuse me for the noise I
kept generating with this issue.

[Stephen Chennney, 2013-12-17 14:26:37]

lgtm

[commit-bot: I haz the power, 2013-12-17 14:26:57]

CQ is trying da patch. Follow status at
https://chromium-status.appspot.com/cq/mitica@adobe.com/104663003/60001

[commit-bot: I haz the power, 2013-12-17 16:49:48]

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

[commit-bot: I haz the power, 2013-12-17 17:14:58]

CQ is trying da patch. Follow status at
https://chromium-status.appspot.com/cq/mitica@adobe.com/104663003/60001

[commit-bot: I haz the power, 2013-12-17 18:04:06]

Change committed as 164026