Refactor dependency_graph.dart.

Refactor dependency_graph.dart.

It multiplexed a bunch of different events onto a single stream. But
every single listener on that stream immediately demuxed them and only
cared about a subset of the events.

So I made separate streams for each event. Other minor clean-ups too.

R=sigmund@google.com, whesse@google.com

Committed: https://github.com/dart-lang/sdk/commit/82df163eca1f025cdfe2169029d64a30432e80bb

[Bob Nystrom, 2017-06-23 23:56:15]

rnystrom@google.com changed reviewers:
+ whesse@google.com

[Bill Hesse, 2017-06-26 14:40:16]

lgtm

[Bob Nystrom, 2017-06-26 23:42:26]

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

[Bob Nystrom, 2017-06-26 23:42:26]

Siggy, I forgot to fix the test when I refactored this. Would you mind reviewing
patch set 3?

Thanks!

[Siggi Cherem (dart-lang), 2017-06-26 23:49:29]

lgtm

[Bob Nystrom, 2017-06-27 00:07:40]

Description was changed from

==========
Refactor dependency_graph.dart.

It multiplexed a bunch of different events onto a single stream. But
every single listener on that stream immediately demuxed them and only
cared about a subset of the events.

So I made separate streams for each event. Other minor clean-ups too.
==========

to

==========
Refactor dependency_graph.dart.

It multiplexed a bunch of different events onto a single stream. But
every single listener on that stream immediately demuxed them and only
cared about a subset of the events.

So I made separate streams for each event. Other minor clean-ups too.

R=sigmund@google.com, whesse@google.com

Committed:
https://github.com/dart-lang/sdk/commit/82df163eca1f025cdfe2169029d64a30432e80bb
==========

[Bob Nystrom, 2017-06-27 00:07:41]

Committed patchset #3 (id:40001) manually as
82df163eca1f025cdfe2169029d64a30432e80bb (presubmit successful).