Make retained size human-readable.

runtime/bin/vmservice/client/lib/src/elements/class_view.dart

Index: runtime/bin/vmservice/client/lib/src/elements/class_view.dart
===================================================================
--- runtime/bin/vmservice/client/lib/src/elements/class_view.dart	(revision 37613)
+++ runtime/bin/vmservice/client/lib/src/elements/class_view.dart	(working copy)
@@ -12,16 +12,19 @@
 @CustomTag('class-view')
 class ClassViewElement extends ObservatoryElement {
   @published Class cls;
+  @observable int retainedBytes;
   ClassViewElement.created() : super.created();
 
   Future<ServiceObject> eval(String text) {
-    return cls.isolate.get(
-        cls.id + "/eval?expr=${Uri.encodeComponent(text)}");
+    return cls.get("eval?expr=${Uri.encodeComponent(text)}");
   }
 
   // TODO(koda): Add no-arg "calculate-link" instead of reusing "eval-link".
-  Future<ServiceObject> retainedSize(String dummy) {
-    return cls.isolate.get(cls.id + "/retained");
+  Future<ServiceObject> retainedSize(var dummy) {
+    return cls.get("retained")
+        .then((ServiceMap obj) {
+          retainedBytes = int.parse(obj['valueAsString']);
+        });
   }
 
   void refresh(var done) {