Drop support for [TreatUndefinedAs=NullString]

Drop support for [TreatUndefinedAs=NullString]

Because it was only used on nullable DOMString types, this does not
change the generated bindings at all, and thus there is no change.

BUG=460722
Committed: https://crrev.com/b3ccf01a59d182eee56040de8624d4b1b01abe73
Cr-Commit-Position: refs/heads/master@{#429590}

[foolip, 2016-11-03 12:19:50]

The CQ bit was checked by foolip@chromium.org to run a CQ dry run

[commit-bot: I haz the power, 2016-11-03 12:20:01]

Dry run: CQ is trying da patch. Follow status at
 
https://chromium-cq-status.appspot.com/v2/patch-status/codereview.chromium.or...

[foolip, 2016-11-03 12:36:41]

foolip@chromium.org changed reviewers:
+ bashi@chromium.org, haraken@chromium.org

[foolip, 2016-11-03 12:36:41]

PTAL

[haraken, 2016-11-03 14:02:39]

LGTM

[foolip, 2016-11-03 14:06:21]

The CQ bit was unchecked by foolip@chromium.org

[foolip, 2016-11-03 14:06:22]

The CQ bit was checked by foolip@chromium.org

[commit-bot: I haz the power, 2016-11-03 14:06:31]

CQ is trying da patch. Follow status at
 
https://chromium-cq-status.appspot.com/v2/patch-status/codereview.chromium.or...

[commit-bot: I haz the power, 2016-11-03 15:17:11]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2016-11-03 15:40:52]

Description was changed from

==========
Drop support for [TreatUndefinedAs=NullString]

Because it was only used on nullable DOMString types, this does not
change the generated bindings at all, and thus there is no change.

BUG=460722
==========

to

==========
Drop support for [TreatUndefinedAs=NullString]

Because it was only used on nullable DOMString types, this does not
change the generated bindings at all, and thus there is no change.

BUG=460722

Committed: https://crrev.com/b3ccf01a59d182eee56040de8624d4b1b01abe73
Cr-Commit-Position: refs/heads/master@{#429590}
==========

[commit-bot: I haz the power, 2016-11-03 15:40:53]

Patchset 1 (id:??) landed as
https://crrev.com/b3ccf01a59d182eee56040de8624d4b1b01abe73
Cr-Commit-Position: refs/heads/master@{#429590}

[bashi, 2016-11-03 23:06:20]

lgtm