Avoid to list internal Arrays in _GetRetainingPath api

runtime/observatory/tests/service/get_retaining_path_rpc_test.dart

Index: runtime/observatory/tests/service/get_retaining_path_rpc_test.dart
diff --git a/runtime/observatory/tests/service/get_retaining_path_rpc_test.dart b/runtime/observatory/tests/service/get_retaining_path_rpc_test.dart
index 74e98c973aa1b19b7e37ce9aa15b886035b83209..b10a95b73cb207e45b638b69cd9855d611ccf0b2 100644
--- a/runtime/observatory/tests/service/get_retaining_path_rpc_test.dart
+++ b/runtime/observatory/tests/service/get_retaining_path_rpc_test.dart
@@ -9,24 +9,20 @@ import 'package:unittest/unittest.dart';
 import 'test_helper.dart';
 
 class _TestClass {
-  _TestClass(this.x, this.y);
+  _TestClass();
   var x;
   var y;
 }
 
-var target1;
-var target2;
-var target3;
-var globalObject;
-var globalList;
+var target1 = new _TestClass();
+var target2 = new _TestClass();
+var target3 = new _TestClass();
+var globalObject = new _TestClass();
+var globalList = new List(100);
 
 void warmup() {
-  target1 = new _TestClass(null, null);
-  target2 = new _TestClass(null, null);
-  globalObject = new _TestClass(target1, target2);
-
-  target3 = new _TestClass(null, null);
-  globalList = new List(100);
+  globalObject.x = target1;
+  globalObject.y = target2;
   globalList[12] = target3;
 }
 
@@ -44,9 +40,10 @@ var tests = [
     var obj = await eval(isolate, 'globalObject');
     var params = {
       'targetId': obj['id'],
-      'limit': 4,
+      'limit': 100,
     };
     var result = await isolate.invokeRpcNoUpgrade('_getRetainingPath', params);
+    expect(result['elements'].length, equals(2));
     expect(result['elements'][1]['value']['name'], equals('globalObject'));
   },
 
@@ -74,10 +71,12 @@ var tests = [
         isolate, '() { var tmp = target1; target1 = null; return tmp;} ()');
     var params = {
       'targetId': target1['id'],
-      'limit': 4,
+      'limit': 100,
     };
     var result = await isolate.invokeRpcNoUpgrade('_getRetainingPath', params);
     expect(result['type'], equals('RetainingPath'));
+    print(result['elements']);
+    expect(result['elements'].length, equals(3));
     expect(result['elements'][1]['parentField']['name'], equals('x'));
     expect(result['elements'][2]['value']['name'], equals('globalObject'));
   },
@@ -87,10 +86,12 @@ var tests = [
         isolate, '() { var tmp = target2; target2 = null; return tmp;} ()');
     var params = {
       'targetId': target2['id'],
-      'limit': 4,
+      'limit': 100,
     };
     var result = await isolate.invokeRpcNoUpgrade('_getRetainingPath', params);
     expect(result['type'], equals('RetainingPath'));
+    print(result['elements']);
+    expect(result['elements'].length, equals(3));
     expect(result['elements'][1]['parentField']['name'], equals('y'));
     expect(result['elements'][2]['value']['name'], equals('globalObject'));
   },
@@ -100,13 +101,15 @@ var tests = [
         isolate, '() { var tmp = target3; target3 = null; return tmp;} ()');
     var params = {
       'targetId': target3['id'],
-      'limit': 4,
+      'limit': 100,
     };
     var result = await isolate.invokeRpcNoUpgrade('_getRetainingPath', params);
     expect(result['type'], equals('RetainingPath'));
+    print(result['elements']);
+    expect(result['elements'].length, equals(3));
     expect(result['elements'][1]['parentListIndex'], equals(12));
     expect(result['elements'][2]['value']['name'], equals('globalList'));
-  },
+  }
 ];
 
 main(args) async => runIsolateTests(args, tests, testeeBefore:warmup);