Add getIsolateID to Service class in dart:developer

sdk/lib/developer/service.dart

Index: sdk/lib/developer/service.dart
diff --git a/sdk/lib/developer/service.dart b/sdk/lib/developer/service.dart
index 9ccf0dccc268ca48fda44572f341057987be6ff3..c1837e80ecb3668769098bdbbc098f447612ccad 100644
--- a/sdk/lib/developer/service.dart
+++ b/sdk/lib/developer/service.dart
@@ -73,6 +73,18 @@ class Service {
     receivePort.close();
     return new ServiceProtocolInfo(uri);
   }
+
+  /// Returns the opaque service id for [isolate] as a [String]. This id can

[Lasse Reichstein Nielsen, 2016/12/01 20:29:05]

id -> ID (both of them)

Not sure what "opaque" means here. Maybe "Returns a [String] token representing
the ID of [isolate]" instead?

Start with a single sentence on the first line, then an empty line, and then
continue with the rest.

Have you considered using a Capability instead of a string as the identifier?
(That obviously won't work if you need to roundtrip the value through non-Dart
code, or store it in JSON, but it is the canonical "opaque capability token"
type in Dart and it can be sent over send ports).

[Cutch, 2016/12/01 20:41:30]

Done.
Done.
Done.
The context of this ID is the service protocol which is a JSON-RPC based
protocol. 

+  /// be used to address an isolate over the service protocol. If the running
+  /// Dart environment does not support the service protocol, this returns null.

[Lasse Reichstein Nielsen, 2016/12/01 20:29:05]

Last sentence: "Returns null if the running Dart environment does not support
the service protocol". Possibly make it a new paragraph.

(It's a good idea to start sentences and paragraphs that talk about return types
with "Returns", it makes them stand out. Also, I think it's crisper that way,
and avoids a "this" :)

[Cutch, 2016/12/01 20:41:30]

Done.

+  static String getServiceIdForIsolate(Isolate isolate) {

[turnidge, 2016/12/01 19:22:44]

getIsolateId?

[Cutch, 2016/12/01 20:41:30]

Done.

+    if (isolate is! Isolate) {
+      throw new ArgumentError.value(isolate,
+                                    'isolate',
+                                    'Must be an Isolate');
+    }
+    return _getIsolateIdFromSendPort(isolate.controlPort);
+  }
 }
 
 /// [sp] will receive a Uri or null.
@@ -87,3 +99,5 @@ external int _getServiceMajorVersion();
 /// Returns the minor version of the service protocol.
 external int _getServiceMinorVersion();
 
+/// Returns the service id for the isolate that owns [sp].
+external String _getIsolateIdFromSendPort(SendPort sp);

[Lasse Reichstein Nielsen, 2016/12/01 20:29:05]

id -> ID.
sp -> sendPort.
(Style guide says: Avoid abbreviations :)

[Cutch, 2016/12/01 20:41:30]

Done.