Fix a bug where breakpoints where not getting properly deleted.

Fix a bug where breakpoints where not getting properly deleted.

This bug was causing it to be impossible to single-step to locations
which had deleted breakpoints.

In fixing this problem, another issue was exposed, where, if we single
step while at a breakpoint, we would hit the same pc twice in the
debugger.  I have added a "skip step" mechanism which allows us to
skip the next single-step after a breakpoint.

Added a test.

Closes #25465

R=johnmccutchan@google.com

Committed: https://github.com/dart-lang/sdk/commit/bf130de6c0fda66ac711b0e21d9db3c714f71444

[turnidge, 2016-01-27 18:52:00]

Description was changed from

==========
Fix a bug where breakpoints where not getting properly deleted.

This bug was causing it to be impossible to single-step to locations
which had deleted breakpoints.

In fixing this problem, another issue was exposed, where, if we single
step while at a breakpoint, we would hit the same pc twice in the
debugger.  I have added a "skip step" mechanism which allows us to
skip the next single-step after a breakpoint.

Added a test.

BUG=25465
==========

to

==========
Fix a bug where breakpoints where not getting properly deleted.

This bug was causing it to be impossible to single-step to locations
which had deleted breakpoints.

In fixing this problem, another issue was exposed, where, if we single
step while at a breakpoint, we would hit the same pc twice in the
debugger.  I have added a "skip step" mechanism which allows us to
skip the next single-step after a breakpoint.

Added a test.

Closes #25465
==========

[turnidge, 2016-01-27 18:52:45]

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

[Cutch, 2016-01-27 19:13:20]

lgtm

[hausner, 2016-01-27 19:22:44]

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

[hausner, 2016-01-27 19:22:44]

DBC: you could make the skip_step 'hack' a bit more local if you define the flag
in the debugger object, not the isolate. The value is only produced and consumed
by the debugger, similar to the stepping_fp_ value.

[turnidge, 2016-01-27 19:39:30]

On 2016/01/27 19:22:44, hausner wrote:
> DBC: you could make the skip_step 'hack' a bit more local if you define the
flag
> in the debugger object, not the isolate. The value is only produced and
consumed
> by the debugger, similar to the stepping_fp_ value.

Thanks Matthias.  Done.

[turnidge, 2016-01-27 19:49:59]

Description was changed from

==========
Fix a bug where breakpoints where not getting properly deleted.

This bug was causing it to be impossible to single-step to locations
which had deleted breakpoints.

In fixing this problem, another issue was exposed, where, if we single
step while at a breakpoint, we would hit the same pc twice in the
debugger.  I have added a "skip step" mechanism which allows us to
skip the next single-step after a breakpoint.

Added a test.

Closes #25465
==========

to

==========
Fix a bug where breakpoints where not getting properly deleted.

This bug was causing it to be impossible to single-step to locations
which had deleted breakpoints.

In fixing this problem, another issue was exposed, where, if we single
step while at a breakpoint, we would hit the same pc twice in the
debugger.  I have added a "skip step" mechanism which allows us to
skip the next single-step after a breakpoint.

Added a test.

Closes #25465

R=johnmccutchan@google.com

Committed:
https://github.com/dart-lang/sdk/commit/bf130de6c0fda66ac711b0e21d9db3c714f71444
==========

[turnidge, 2016-01-27 19:50:00]

Committed patchset #4 (id:60001) manually as
bf130de6c0fda66ac711b0e21d9db3c714f71444 (presubmit successful).