Move FutureImpl and CompleterImpl from coreimpl to core, while also making them private.

lib/core/future.dart

 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 /**
  * A [Future] is used to obtain a value sometime in the future.  Receivers of a
  * [Future] can obtain the value by passing a callback to [then]. For example:
  *
  *     Future<int> future = getFutureFromSomewhere();
  *     future.then((value) {
@@ skipping 11 matching lines @@
  *      called in sequence, until one returns true.
  *   3. handlers registered with [onComplete] are called
  *   4. if the future failed, and at least one handler was registered with
  *      [then], and no handler registered with [handleException] returned
  *      [:true:], then the exception is thrown.
  *
  * Use a [Completer] to create and change the state of a [Future].
  */
 abstract class Future<T> {
   /** A future whose value is immediately available. */
-  factory Future.immediate(T value) => new FutureImpl<T>.immediate(value);
+  factory Future.immediate(T value) => new _FutureImpl<T>.immediate(value);
 
   /** The value provided. Throws an exception if [hasValue] is false. */
   T get value;
 
   /**
    * Exception that occurred ([:null:] if no exception occured). This property
    * throws a [FutureNotCompleteException] if it is used before this future is
    * completes.
    */
   Object get exception;
@@ skipping 111 matching lines @@
  *     // later when value is available, call:
  *     completer.complete(value);
  *
  *     // alternatively, if the service cannot produce the value, it
  *     // can provide an exception:
  *     completer.completeException(exception);
  *
  */
 abstract class Completer<T> {
 
-  factory Completer() => new CompleterImpl<T>();
+  factory Completer() => new _CompleterImpl<T>();
 
   /** The future that will contain the value produced by this completer. */
   Future get future;
 
   /** Supply a value for [future]. */
   void complete(T value);
 
   /**
    * Indicate in [future] that an exception occured while trying to produce its
    * value. The argument [exception] should not be [:null:]. A [stackTrace]
@@ skipping 78 matching lines @@
       future.handleException((exception) {
         if (!result.isComplete) {
           completer.completeException(exception, future.stackTrace);
         }
         return true;
       });
     }
     return result;
   }
 }