Implement ClassMirror.superclass with internal code for ordinary (but not function type) classes. R…

runtime/lib/mirrors_impl.dart

Index: runtime/lib/mirrors_impl.dart
===================================================================
--- runtime/lib/mirrors_impl.dart	(revision 25507)
+++ runtime/lib/mirrors_impl.dart	(working copy)
@@ -450,6 +450,14 @@
 
   var _superclass;
   ClassMirror get superclass {
+    if (_superclass == null) {
+      Type supertype = _supertype(_reflectee);
+      if (supertype == null) {
+        // Object has no superclass.
+        return null;
+      }
+      _superclass = reflectClass(supertype);
+    }
     if (_superclass is! Mirror) {
       _superclass = _superclass.resolve(mirrors);
     }
@@ -592,6 +600,9 @@
   static _library(reflectee)
       native "ClassMirror_library";
 
+  static _supertype(reflectee)
+      native "ClassMirror_supertype";
+
   _computeMembers(reflectee)
       native "ClassMirror_members";