Add 'dart:debugger' library

Add 'dart:debugger' library

- Add the 'dart:debugger' library.
- Add the 'Debugger' class.
- Add explicit Dart breakpoint triggered by a call to: Debugger.breakHere();
- Add Debugger.breakHereIf(bool expr)

R=hausner@google.com, turnidge@google.com

Committed: https://code.google.com/p/dart/source/detail?r=45529

[Cutch, 2015-05-04 23:46:34]

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

[hausner, 2015-05-05 00:16:27]

LGTM with a few naming suggestions. Feel free to ignore.

This has been a long-standing feature request. Check out bug 10536.

https://codereview.chromium.org/1116263004/diff/1/runtime/lib/debugger.dart
File runtime/lib/debugger.dart (right):

https://codereview.chromium.org/1116263004/diff/1/runtime/lib/debugger.dart#n...
runtime/lib/debugger.dart:8: /* patch */ static void breakpoint() native
"Debugger_breakpoint";
Is this name dictated by some spec? I think a verb would make more sense if you
have the liberty to choose. Debugger.suspend() or Debugger.halt() or something
is maybe more descriptive than Debugger.breakpoint().

Unfortunately, Debugger.break() doesn't work because break is a keyword.

There is a bit of bikeshedding about this in dartbug.com/10536

https://codereview.chromium.org/1116263004/diff/1/runtime/vm/debugger.cc
File runtime/vm/debugger.cc (right):

https://codereview.chromium.org/1116263004/diff/1/runtime/vm/debugger.cc#newc...
runtime/vm/debugger.cc:2278: void Debugger::ExplicitBreakpoint() {
SignalDebugBreak()  ?

https://codereview.chromium.org/1116263004/diff/1/sdk/lib/debugger/debugger.dart
File sdk/lib/debugger/debugger.dart (right):

https://codereview.chromium.org/1116263004/diff/1/sdk/lib/debugger/debugger.d...
sdk/lib/debugger/debugger.dart:1: // Copyright (c) 2014, the Dart project
authors.  Please see the AUTHORS file
2015

https://codereview.chromium.org/1116263004/diff/1/sdk/lib/debugger/debugger.d...
sdk/lib/debugger/debugger.dart:14: print('Debugger.breakpoint not supported by
your embedder.');
... by this embedder ... ?

or: on this platform

[Cutch, 2015-05-05 02:38:53]

https://codereview.chromium.org/1116263004/diff/1/runtime/lib/debugger.dart
File runtime/lib/debugger.dart (right):

https://codereview.chromium.org/1116263004/diff/1/runtime/lib/debugger.dart#n...
runtime/lib/debugger.dart:8: /* patch */ static void breakpoint() native
"Debugger_breakpoint";
On 2015/05/05 00:16:26, hausner wrote:
> Is this name dictated by some spec? I think a verb would make more sense if
you
> have the liberty to choose. Debugger.suspend() or Debugger.halt() or something
> is maybe more descriptive than Debugger.breakpoint().
> 
> Unfortunately, Debugger.break() doesn't work because break is a keyword.
> 
> There is a bit of bikeshedding about this in dartbug.com/10536

I went with "breakHere" and "breakHereIf".

https://codereview.chromium.org/1116263004/diff/1/runtime/vm/debugger.cc
File runtime/vm/debugger.cc (right):

https://codereview.chromium.org/1116263004/diff/1/runtime/vm/debugger.cc#newc...
runtime/vm/debugger.cc:2278: void Debugger::ExplicitBreakpoint() {
On 2015/05/05 00:16:27, hausner wrote:
> SignalDebugBreak()  ?

I went with BreakHere and changed the behaviour. PTAL.

https://codereview.chromium.org/1116263004/diff/1/sdk/lib/debugger/debugger.dart
File sdk/lib/debugger/debugger.dart (right):

https://codereview.chromium.org/1116263004/diff/1/sdk/lib/debugger/debugger.d...
sdk/lib/debugger/debugger.dart:1: // Copyright (c) 2014, the Dart project
authors.  Please see the AUTHORS file
On 2015/05/05 00:16:27, hausner wrote:
> 2015

Done.

https://codereview.chromium.org/1116263004/diff/1/sdk/lib/debugger/debugger.d...
sdk/lib/debugger/debugger.dart:14: print('Debugger.breakpoint not supported by
your embedder.');
On 2015/05/05 00:16:27, hausner wrote:
> ... by this embedder ... ?
> 
> or: on this platform
> 
> 
> 

Done.

[turnidge, 2015-05-05 16:33:20]

lgtm

[Cutch, 2015-05-05 17:05:57]

Committed patchset #3 (id:40001) manually as 45529 (presubmit successful).