Add view for MegamorphicCache. Update view for ObjectPool.

runtime/observatory/lib/src/service/object.dart

Index: runtime/observatory/lib/src/service/object.dart
diff --git a/runtime/observatory/lib/src/service/object.dart b/runtime/observatory/lib/src/service/object.dart
index 6e81583f654fceafab648b59a8fc8bd428d0c502..acb3edff8293467f95efff90b6d5c2789a60da22 100644
--- a/runtime/observatory/lib/src/service/object.dart
+++ b/runtime/observatory/lib/src/service/object.dart
@@ -231,6 +231,9 @@ abstract class ServiceObject extends Observable {
           case 'LocalVarDescriptors':
             obj = new LocalVarDescriptors._empty(owner);
             break;
+          case 'MegamorphicCache':
+            obj = new MegamorphicCache._empty(owner);
+            break;
           case 'ObjectPool':
             obj = new ObjectPool._empty(owner);
             break;
@@ -3332,6 +3335,28 @@ class ICData extends HeapObject {
   }
 }
 
+class MegamorphicCache extends HeapObject {
+  @observable int mask;
+  @observable Instance buckets;
+
+  bool get canCache => false;
+  bool get immutable => false;
+
+  MegamorphicCache._empty(ServiceObjectOwner owner) : super._empty(owner);
+
+  void _update(ObservableMap map, bool mapIsRef) {
+    _upgradeCollection(map, isolate);
+    super._update(map, mapIsRef);
+
+    if (mapIsRef) {
+      return;
+    }
+
+    mask = map['_mask'];
+    buckets = map['_buckets'];
+  }
+}
+
 class Instructions extends HeapObject {
   bool get canCache => false;
   bool get immutable => true;