Retaining path in Observatory.

Retaining path in Observatory.

Add retaining_path instance command to VM service, exposed in the Observatory
with a [find] eval-link in instance view. By default shows up to 10 elements,
possibly followed by [find more] which doubles the number of elements shown.

Change RetainingPath to include the object itself.

Always include an id in Object::PrintJSONImpl, to avoid instance-ref crashing on
internal objects.

R=johnmccutchan@google.com

Committed: https://code.google.com/p/dart/source/detail?r=36516

[Cutch, 2014-05-22 03:10:12]

lgtm after adding service tests.

https://codereview.chromium.org/292663012/diff/40001/runtime/vm/service.cc
File runtime/vm/service.cc (right):

https://codereview.chromium.org/292663012/diff/40001/runtime/vm/service.cc#ne...
runtime/vm/service.cc:933: intptr_t limit;
Add a service test success and failure cases.

https://codereview.chromium.org/292663012/diff/40001/runtime/vm/service.cc#ne...
runtime/vm/service.cc:936: js->num_arguments());
return true;

[koda, 2014-05-22 17:27:47]

Also had to avoid the toString() call inside {{}} to make JS version work.

https://codereview.chromium.org/292663012/diff/40001/runtime/vm/service.cc
File runtime/vm/service.cc (right):

https://codereview.chromium.org/292663012/diff/40001/runtime/vm/service.cc#ne...
runtime/vm/service.cc:933: intptr_t limit;
On 2014/05/22 03:10:12, Cutch wrote:
> Add a service test success and failure cases.

Done.

https://codereview.chromium.org/292663012/diff/40001/runtime/vm/service.cc#ne...
runtime/vm/service.cc:936: js->num_arguments());
On 2014/05/22 03:10:12, Cutch wrote:
> return true;

Done.

[koda, 2014-05-22 17:31:58]

Committed patchset #4 manually as r36516 (presubmit successful).