VM: Support calling through getters in InstanceMirror.delegate. Implement without accessing private…

runtime/lib/mirrors_impl.dart

Index: runtime/lib/mirrors_impl.dart
diff --git a/runtime/lib/mirrors_impl.dart b/runtime/lib/mirrors_impl.dart
index e057fd223886d1cdbe22a722c0487d4c3a40d3a1..63f1828b32b894c76a6c78a0379e3c7e57590078 100644
--- a/runtime/lib/mirrors_impl.dart
+++ b/runtime/lib/mirrors_impl.dart
@@ -283,17 +283,22 @@ class _LocalInstanceMirror extends _LocalObjectMirror
   get reflectee => _reflectee;
 
   delegate(Invocation invocation) {
-    if (_invokeOnClosure == null) {
-      // TODO(ahe): This is a total hack.  We're using the mirror
-      // system to access a private field in a different library.  For
-      // some reason, that works.  On the other hand, calling a
-      // private method does not work.
-      ClassMirror invocationImplClass = reflect(invocation).type;
-      Symbol fieldName = MirrorSystem.getSymbol('_invokeOnClosure',
-                                                invocationImplClass.owner);
-      _invokeOnClosure = invocationImplClass.getField(fieldName).reflectee;
-    }
-    return _invokeOnClosure(reflectee, invocation);
+    if (invocation.isMethod) {
+      return this.invoke(invocation.memberName,
+                         invocation.positionalArguments,
+                         invocation.namedArguments).reflectee;
+    }
+    if (invocation.isGetter) {
+      return this.getField(invocation.memberName).reflectee;
+    }
+    if (invocation.isSetter) {
+      var unwrapped = _n(invocation.memberName);
+      var withoutEqual = _s(unwrapped.substring(0, unwrapped.length - 1));
+      var arg = invocation.positionalArguments[0];
+      this.setField(withoutEqual, arg).reflectee;
+      return arg;
+    }
+    throw "UNREACHABLE";
   }
 
   String toString() => 'InstanceMirror on ${Error.safeToString(_reflectee)}';