Fix stale key names in get_isolate_rpc_test.

runtime/observatory/tests/service/get_isolate_rpc_test.dart

Index: runtime/observatory/tests/service/get_isolate_rpc_test.dart
diff --git a/runtime/observatory/tests/service/get_isolate_rpc_test.dart b/runtime/observatory/tests/service/get_isolate_rpc_test.dart
index 74940c7299f25ce7aa3519c2a12b06c036a3b337..f03ec751240f8d5383539fa98fc3880a778814f0 100644
--- a/runtime/observatory/tests/service/get_isolate_rpc_test.dart
+++ b/runtime/observatory/tests/service/get_isolate_rpc_test.dart
@@ -23,8 +23,8 @@ var tests = [
     expect(result['pauseOnExit'], isFalse);
     expect(result['pauseEvent']['type'], equals('Event'));
     expect(result['error'], isNull);
-    expect(result['numZoneHandles'], isPositive);
-    expect(result['numScopedHandles'], isPositive);
+    expect(result['_numZoneHandles'], isPositive);
+    expect(result['_numScopedHandles'], isPositive);
     expect(result['rootLib']['type'], equals('@Library'));
     expect(result['libraries'].length, isPositive);
     expect(result['libraries'][0]['type'], equals('@Library'));