Refactor the set command in Observatory debugger.

Refactor the set command in Observatory debugger.

- set with 0/1 args now can be used to query current setting value
- added completion for set command
- added up-is-down option to provide gdb-like behavior for up/down commands

BUG=
R=johnmccutchan@google.com

Committed: https://github.com/dart-lang/sdk/commit/5b6136fdfb0addf98abc52fff1c605a84bfd465c

[turnidge, 2015-08-07 19:50:25]

turnidge@google.com changed reviewers:
+ johnmccutchan@google.com

[Cutch, 2015-08-07 19:55:10]

LGTM with some comments

https://codereview.chromium.org/1277173004/diff/20001/runtime/observatory/lib...
File runtime/observatory/lib/src/elements/debugger.dart (right):

https://codereview.chromium.org/1277173004/diff/20001/runtime/observatory/lib...
runtime/observatory/lib/src/elements/debugger.dart:606: "                       
# {'all', 'none', 'unhandled'}\n"
can you do string interpolation here and below?

e.g.:

# ${_boeValues}

https://codereview.chromium.org/1277173004/diff/20001/runtime/observatory/lib...
runtime/observatory/lib/src/elements/debugger.dart:1148: SettingsGroup settings
= new SettingsGroup('debugger');
nit: add final

https://codereview.chromium.org/1277173004/diff/20001/runtime/observatory/lib...
runtime/observatory/lib/src/elements/debugger.dart:1196: _upIsDown =
settings.get('up-is-down');
maybe factor this into a helper:

_loadSettings();

_loadSettings() {
  _upIsDown = settings.get('up-is-down');
}

https://codereview.chromium.org/1277173004/diff/20001/runtime/observatory/lib...
runtime/observatory/lib/src/elements/debugger.dart:1426: breakOnException =
event.exceptions;
Should this update the setting?

[turnidge, 2015-08-07 20:16:42]

https://codereview.chromium.org/1277173004/diff/20001/runtime/observatory/lib...
File runtime/observatory/lib/src/elements/debugger.dart (right):

https://codereview.chromium.org/1277173004/diff/20001/runtime/observatory/lib...
runtime/observatory/lib/src/elements/debugger.dart:606: "                       
# {'all', 'none', 'unhandled'}\n"
On 2015/08/07 19:55:10, Cutch wrote:
> can you do string interpolation here and below?
> 
> e.g.:
> 
> # ${_boeValues}

Done.

https://codereview.chromium.org/1277173004/diff/20001/runtime/observatory/lib...
runtime/observatory/lib/src/elements/debugger.dart:1148: SettingsGroup settings
= new SettingsGroup('debugger');
On 2015/08/07 19:55:10, Cutch wrote:
> nit: add final

Done.

https://codereview.chromium.org/1277173004/diff/20001/runtime/observatory/lib...
runtime/observatory/lib/src/elements/debugger.dart:1196: _upIsDown =
settings.get('up-is-down');
On 2015/08/07 19:55:10, Cutch wrote:
> maybe factor this into a helper:
> 
> _loadSettings();
> 
> _loadSettings() {
>   _upIsDown = settings.get('up-is-down');
> }

Done.

https://codereview.chromium.org/1277173004/diff/20001/runtime/observatory/lib...
runtime/observatory/lib/src/elements/debugger.dart:1426: breakOnException =
event.exceptions;
Discussed offline -- this is all we need to do, but maybe this should become
some sort of per-isolate setting.

[turnidge, 2015-08-07 20:22:26]

Committed patchset #3 (id:40001) manually as
5b6136fdfb0addf98abc52fff1c605a84bfd465c (presubmit successful).