Add error-intercept for Completer.completeError and StreamController.addError.

Add error-intercept for Completer.completeError and StreamController.addError.

BUG= http://dartbug.com/15105
R=sgjesse@google.com

Committed: https://code.google.com/p/dart/source/detail?r=40308

[Lasse Reichstein Nielsen, 2014-09-10 08:58:15]

lrn@google.com changed reviewers:
+ floitsch@google.com, sgjesse@google.com

[Søren Gjesse, 2014-09-10 09:34:18]

LGTM

[Søren Gjesse, 2014-09-10 09:35:01]

On 2014/09/10 09:34:18, Søren Gjesse wrote:
> LGTM

Btw.: How about some tests?

[nweiz, 2014-09-10 19:54:46]

On 2014/09/10 08:58:15, Lasse Reichstein Nielsen wrote:

DBC

This still doesn't support intercepting of errors in [new Future] or [new
Future.microtask]. These errors are caught within the dart:async infrastructure
so [{register,run}Callback] can't catch them, but they're not passed to
[errorCallback] either.

[Lasse Reichstein Nielsen, 2014-09-10 20:16:36]

On 2014/09/10 19:54:46, nweiz wrote:

> This still doesn't support intercepting of errors in [new Future] or [new
> Future.microtask]. These errors are caught within the dart:async
infrastructure
> so [{register,run}Callback] can't catch them, but they're not passed to
> [errorCallback] either.

Ack, I'll check that. Future.sync gets handled because it uses new Future.error,
maybe the other ones do too.

[Lasse Reichstein Nielsen, 2014-09-11 07:15:14]

I guess this should intercept all places where a synchronous error is turned
into an asynchronous one.
That means all places where a callback throws, that isn't a registered callback.
This include the Future, Future.sync and Future.microtask calls. These are all
run in the current zone, but not as registered callbacks.

I'll have to go through the async lib and see if there are more, and if there
are cases where we can avoid intercepting because we are just moving existing
async errors into a new completer/controller/future.

[Lasse Reichstein Nielsen, 2014-09-11 12:44:37]

Updated and added tests.

PTAL

[Søren Gjesse, 2014-09-12 06:45:55]

lgtm

[Lasse Reichstein Nielsen, 2014-09-16 10:51:15]

Committed patchset #4 (id:60001) manually as 40308 (presubmit successful).