Revert changes to Future.chain() and Future.transform() from http://codereview.chromium.org/10517006

corelib/src/future.dart

Index: corelib/src/future.dart
===================================================================
--- corelib/src/future.dart	(revision 8478)
+++ corelib/src/future.dart	(working copy)
@@ -97,6 +97,9 @@
    *
    * If an exception occurs (received by this future, or thrown by
    * [transformation]) then the returned future will receive the exception.
+   *  
+   * You must not add exception handlers to [this] future prior to calling 
+   * transform, and any you add afterwards will not be invoked.
    */
   Future transform(transformation(T value));
 
@@ -111,6 +114,9 @@
     * If an exception occurs (received by this future, thrown by
     * [transformation], or received by the future returned by [transformation])
     * then the returned future will receive the exception.
+    *
+    * You must not add exception handlers to [this] future prior to calling 
+    * chain, and any you add afterwards will not be invoked.
     */
    Future chain(Future transformation(T value));
 }