Reland https://code.google.com/p/dart/source/detail?r=29315:

Reland https://code.google.com/p/dart/source/detail?r=29315:
- Make sure to keep the main/control port opened until the
  isolate is finished.
- Account for the number of opened control ports to be able
  to determine whether there are live ports.
- Ensure that the spawned isolated is kept alive until the
  initial startup message can be handled.
- Add more isolate tracing output.
- Use the control port for the debugger id.

Committed: https://code.google.com/p/dart/source/detail?r=29323

[Ivan Posva, 2013-10-27 14:33:16]

TBR (relanding previously reviewed code).

-Ivan

https://codereview.chromium.org/47573002/diff/1/runtime/lib/isolate_patch.dart
File runtime/lib/isolate_patch.dart (right):

https://codereview.chromium.org/47573002/diff/1/runtime/lib/isolate_patch.dar...
runtime/lib/isolate_patch.dart:167: var keepAlivePort = new RawReceivePort();
This is the main change from the previously reviewed code.

https://codereview.chromium.org/47573002/diff/1/runtime/lib/isolate_patch.dar...
runtime/lib/isolate_patch.dart:178: keepAlivePort.close();
ditto.

https://codereview.chromium.org/47573002/diff/1/runtime/vm/debugger.cc
File runtime/vm/debugger.cc (left):

https://codereview.chromium.org/47573002/diff/1/runtime/vm/debugger.cc#oldcod...
runtime/vm/debugger.cc:1927: isolate_id_ =
PortMap::CreatePort(isolate->message_handler());
Since the main port (aka control port) survives to the end of the isolate, we
can now reuse that port for debugger identification.

https://codereview.chromium.org/47573002/diff/1/runtime/vm/port.cc
File runtime/vm/port.cc (right):

https://codereview.chromium.org/47573002/diff/1/runtime/vm/port.cc#newcode85
runtime/vm/port.cc:85: if (FLAG_trace_isolates) {
Added tracing support.

https://codereview.chromium.org/47573002/diff/1/runtime/vm/port.cc#newcode146
runtime/vm/port.cc:146: if (FLAG_trace_isolates) {
ditto

[Ivan Posva, 2013-10-27 14:34:32]

Committed patchset #1 manually as r29323 (presubmit successful).