Teach the Observatory about WeakProperties (ephemerons).

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

Index: runtime/bin/vmservice/observatory/lib/src/service/object.dart
diff --git a/runtime/bin/vmservice/observatory/lib/src/service/object.dart b/runtime/bin/vmservice/observatory/lib/src/service/object.dart
index 2e92b8b2fa4b477b45dd345aabbcf38a14c30fcb..ef4b68a1a22d53774c0024a34caa86639b7cdfd6 100644
--- a/runtime/bin/vmservice/observatory/lib/src/service/object.dart
+++ b/runtime/bin/vmservice/observatory/lib/src/service/object.dart
@@ -50,6 +50,7 @@ abstract class ServiceObject extends Observable {
   bool get isSentinel => vmType == 'Sentinel';
   bool get isString => vmType == 'String';
   bool get isType => vmType == 'Type';
+  bool get isWeakProperty => vmType == 'WeakProperty';
 
   /// The complete service url of this object.
   @reflectable String get link => _owner.relativeLink(_id);
@@ -120,6 +121,7 @@ abstract class ServiceObject extends Observable {
       case 'Smi':
       case 'String':
       case 'Type':
+      case 'WeakProperty':
         obj = new Instance._empty(owner);
         break;
       case 'Isolate':
@@ -1487,6 +1489,8 @@ class Instance extends ServiceObject {
   @observable var nativeFields;
   @observable var elements;
   @observable var userName;
+  @observable Instance key;  // If a WeakProperty.
+  @observable Instance value;  // If a WeakProperty.

[Cutch, 2014/09/04 15:27:24]

I wonder if we should start subclassing Instance so we don't keep adding fields
for each instance type. Just a thought, not necessary for this change.

[rmacnak, 2014/09/04 20:36:07]

Right, and there are a lot more special Instance types this doesn't even handle
yet.

 
   bool get isClosure => closureFunc != null;
 
@@ -1513,6 +1517,8 @@ class Instance extends ServiceObject {
     elements = map['elements'];
     typeClass = map['type_class'];
     userName = map['user_name'];
+    key = map['key'];
+    value = map['value'];
 
     // We are fully loaded.
     _loaded = true;