IDL: Add support for [TreatNullAs=EmptyString]

IDL: Add support for [TreatNullAs=EmptyString]

[TreatNullAs=NullString] was already supported, and still is, but is
non-standard.  [TreatNullAs=EmptyString] is what Web IDL has and what is
used in specifications to describe required behavior.

There are cases where web-exposed behavior relating to handling of null
is wrong today, and where using [TreatNullAs=EmptyString] instead would
be the natural fix.

BUG=391194
Committed: https://src.chromium.org/viewvc/blink?view=rev&revision=177561

[Jens Widell, 2014-07-04 08:57:31]

PTAL

Step one in the plan outlined in bug 391194.

[haraken, 2014-07-04 10:42:53]

On 2014/07/04 08:57:31, Jens Lindström wrote:
> PTAL
> 
> Step one in the plan outlined in bug 391194.

Are you going to completely deprecate [TreatNullAsNullString]?

I agree that this change is moving us forward but I want to make sure where
we're going. Having both [TreatNullAsNullString] and [TreatNullAsEmptyString]
are very confusing.

[Jens Widell, 2014-07-04 11:11:49]

On 2014/07/04 10:42:53, haraken wrote:
> On 2014/07/04 08:57:31, Jens Lindström wrote:
> > PTAL
> > 
> > Step one in the plan outlined in bug 391194.
> 
> Are you going to completely deprecate [TreatNullAsNullString]?
> 
> I agree that this change is moving us forward but I want to make sure where
> we're going. Having both [TreatNullAsNullString] and [TreatNullAsEmptyString]
> are very confusing.

Assuming we can, I absolute think we should. Having both is unfortunate. I don't
think we will need to keep NullString for cases where the relevant spec has
EmptyString, but I'm not sure. Depends on whether it's a significant
optimization in any case (which I doubt, but haven't ruled out.)

[haraken, 2014-07-04 14:37:48]

On 2014/07/04 11:11:49, Jens Lindström wrote:
> On 2014/07/04 10:42:53, haraken wrote:
> > On 2014/07/04 08:57:31, Jens Lindström wrote:
> > > PTAL
> > > 
> > > Step one in the plan outlined in bug 391194.
> > 
> > Are you going to completely deprecate [TreatNullAsNullString]?
> > 
> > I agree that this change is moving us forward but I want to make sure where
> > we're going. Having both [TreatNullAsNullString] and
[TreatNullAsEmptyString]
> > are very confusing.
> 
> Assuming we can, I absolute think we should. Having both is unfortunate. I
don't
> think we will need to keep NullString for cases where the relevant spec has
> EmptyString, but I'm not sure. Depends on whether it's a significant
> optimization in any case (which I doubt, but haven't ruled out.)

LGTM. We should definitely try.

[Jens Widell, 2014-07-04 14:45:49]

The CQ bit was checked by jl@opera.com

[commit-bot: I haz the power, 2014-07-04 14:46:39]

CQ is trying da patch. Follow status at
 https://chromium-status.appspot.com/cq/jl@opera.com/368313005/1

[commit-bot: I haz the power, 2014-07-04 15:29:38]

FYI, CQ is re-trying this CL (attempt #1).
The failing builders are:
  linux_blink_dbg on tryserver.blink
(http://build.chromium.org/p/tryserver.blink/builders/linux_blink_dbg/builds/1...)
  mac_blink_compile_dbg on tryserver.blink
(http://build.chromium.org/p/tryserver.blink/builders/mac_blink_compile_dbg/bu...)
  win_blink_compile_dbg on tryserver.blink
(http://build.chromium.org/p/tryserver.blink/builders/win_blink_compile_dbg/bu...)

[commit-bot: I haz the power, 2014-07-04 15:36:53]

The CQ bit was unchecked by commit-bot@chromium.org

[commit-bot: I haz the power, 2014-07-04 15:36:54]

Try jobs failed on following builders:
  mac_blink_compile_dbg on tryserver.blink
(http://build.chromium.org/p/tryserver.blink/builders/mac_blink_compile_dbg/bu...)

[Jens Widell, 2014-07-05 07:55:13]

The CQ bit was checked by jl@opera.com

[commit-bot: I haz the power, 2014-07-05 07:56:24]

CQ is trying da patch. Follow status at
 https://chromium-status.appspot.com/cq/jl@opera.com/368313005/20001

[commit-bot: I haz the power, 2014-07-05 09:01:06]

Change committed as 177561