Added ClosureMirror to dart:mirrors. Added Dart_ClosureFunction to the

lib/mirrors/mirrors.dart

Index: lib/mirrors/mirrors.dart
===================================================================
--- lib/mirrors/mirrors.dart	(revision 9796)
+++ lib/mirrors/mirrors.dart	(working copy)
@@ -157,6 +157,38 @@
 }
 
 /**
+ * A [ClosureMirror] reflects a closure. Closures are special, because we do not
+ * wish to reflect the internals of a particular closure implementation. And
+ * yet, we need access to details of the closure internals - for example, its
+ * enclosing context and its source code.
+ */
+interface ClosureMirror extends InstanceMirror {
+
+  /**
+   * Return the source code for the closure, if available.
+   */ 
+  String source();
+  
+  /**
+   * Call the closure. The arguments given in the descriptor need to be
+   * ObjectMirrors or values. Asynchronous.
+   */  
+  Future<ObjectMirror> apply(List<Object> positionalArguments,
+                             [Map<String,Object> namedArguments]); 
+
+  /**
+   * Look up the value of name in the scope of the closure. The result is a
+   * mirror on that value. Asynchronous.
+   */
+  Future<ObjectMirror> findInContext(String name);
+
+  /**
+   * Return a mirror on the function of this closure.
+   */
+  MethodMirror function();
+}
+
+/**
  * A [TypeMirror] reflects a Dart language class, interface, typedef
  * or type variable.
  */