dart2js_html: Fix for issue 29538 - some returned lists may be null

dart2js_html: Fix for issue 29538 - some returned lists may be null

Annotate querySelectorAll as not-null to recover code quality.

R=sigmund@google.com

Committed: https://github.com/dart-lang/sdk/commit/ea2c9cba39a4350e0f0b0e960ed08c80e0a998a3

[sra1, 2017-05-03 21:18:45]

Patchset #1 (id:1) has been deleted

[Siggi Cherem (dart-lang), 2017-05-03 21:22:37]

sigmund@google.com changed reviewers:
+ sigmund@google.com

[Siggi Cherem (dart-lang), 2017-05-03 21:22:38]

lgtm

[sra1, 2017-05-03 21:26:49]

Description was changed from

==========
dart2js_html: Fix for issue 29538 - some returned lists may be null

Annotate querySelectorAll as not-null to recover code quality.
==========

to

==========
dart2js_html: Fix for issue 29538 - some returned lists may be null

Annotate querySelectorAll as not-null to recover code quality.

R=sigmund@google.com

Committed:
https://github.com/dart-lang/sdk/commit/ea2c9cba39a4350e0f0b0e960ed08c80e0a998a3
==========

[sra1, 2017-05-03 21:26:50]

Committed patchset #1 (id:20001) manually as
ea2c9cba39a4350e0f0b0e960ed08c80e0a998a3 (presubmit successful).

[Alan Knight, 2017-05-04 17:52:30]

alanknight@google.com changed reviewers:
+ alanknight@google.com

[Alan Knight, 2017-05-04 17:52:30]

So this is making it the default for things to be able to return null. Or how
often does the condition that native_type is not the same as return_type?  But
if it works for you folks, I guess that's fine.

[sra1, 2017-05-04 18:17:37]

On 2017/05/04 17:52:30, Alan Knight wrote:
> So this is making it the default for things to be able to return null. Or how
> often does the condition that native_type is not the same as return_type?  But
> if it works for you folks, I guess that's fine.

All lists fall into this bucket. The interface is e.g. List<Node>, the concrete
type is NodeList.
There are 43 changes, so it happens 43 times.
We have had several bugs because something could be null but the annotation lied
and dart2js optimized `x==null` to `false`.
We should opt-in to non-nullablilty via the metadata table only when we are
certain.