[dart:developer] Improve documentation of Service.getIsolateId and Service.getObjectId

This CL addresses https://dart-review.googlesource.com/c/sdk/+/317220/comment/7e05218f_882e21cd/

CoreLibraryReviewExempt: This CL does not change any APIs, it just adds
an @Since annotation to a method.
Change-Id: I4187c50498668553806bb2eee6584114363b417a
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/320900
Reviewed-by: Ben Konyi <bkonyi@google.com>
Reviewed-by: Nate Bosch <nbosch@google.com>
Commit-Queue: Derek Xu <derekx@google.com>

CHANGELOG.md

@@ -18,6 +18,12 @@
 
 ### Libraries
 
+#### `dart:developer`
+
+- Deprecated the `Service.getIsolateID` method.
+- Added `getIsolateId` method to `Service`.
+- Added `getObjectId` method to `Service`.
+
 #### `dart:io`
 
 - **Breaking change** [#53005][]: The headers returned by

pkg/vm_service/test/developer_service_get_isolate_id_test.dart

@@ -26,7 +26,9 @@ Future testeeMain() async {
   childIsolate = await iso.Isolate.spawn(spawnEntry, 0);
   // Assign the id for this isolate and it's child to strings so they can
   // be read by the tester.
+  // ignore: sdk_version_since
   selfId = Service.getIsolateId(iso.Isolate.current)!;
+  // ignore: sdk_version_since
   childId = Service.getIsolateId(childIsolate)!;
   debugger();
 }

sdk/lib/developer/developer.dart

@@ -73,7 +73,7 @@
 /// {@category Core}
 library dart.developer;
 
-import 'dart:_internal' show checkNotNullable;
+import 'dart:_internal' show checkNotNullable, Since;
 import 'dart:async';
 import 'dart:collection';
 import 'dart:convert';

sdk/lib/developer/service.dart

@@ -102,6 +102,7 @@ final class Service {
   ///
   /// Returns null if the running Dart environment does not support the service
   /// protocol.
+  @Since('3.2')
   static String? getIsolateId(Isolate isolate) {
     // TODO: When NNBD is complete, delete the following line.
     ArgumentError.checkNotNull(isolate, 'isolate');