Updates the corelib to the new default specification for interfaces and new factory syntax

corelib/src/future.dart

Index: corelib/src/future.dart
diff --git a/corelib/src/future.dart b/corelib/src/future.dart
index a044700b3f24359530492b7ab258c10defae1b1b..03f7cd5aa024ffdccd2a7a8ceff3c1af2d902ad7 100644
--- a/corelib/src/future.dart
+++ b/corelib/src/future.dart
@@ -20,7 +20,7 @@
  *   });
  *
  */
-interface Future<T> factory FutureImpl<T> {
+interface Future<T> default FutureImpl<T> {
 
   /**
    * The value this future provided.  (If called when hasValue
@@ -94,7 +94,7 @@ interface Future<T> factory FutureImpl<T> {
  *   completer.completeException(exception);
  *
  */
-interface Completer<T> factory CompleterImpl<T> {
+interface Completer<T> default CompleterImpl<T> {
 
   /** Create a completer */
   Completer();