fix all instances of "the the"

sdk/lib/async/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.
 
 part of dart.async;
 
 /**
  * An object representing a delayed computation.
  *
  * A [Future] is used to represent a potential value, or error,
@@ skipping 441 matching lines @@
    * and the returned future completes with the same error and stack trace
    * as this future.
    *
    * If `test` returns `true`,
    * [onError] is called with the error and possibly stack trace,
    * and the returned future is completed with the result of this call
    * in exactly the same way as for [then]'s `onError`.
    *
    * If `test` is omitted, it defaults to a function that always returns true.
    * The `test` function should not throw, but if it does, it is handled as
-   * if the the `onError` function had thrown.
+   * if the `onError` function had thrown.
    *
    * Example:
    *
    *     foo
    *       .catchError(..., test: (e) => e is ArgumentError)
    *       .catchError(..., test: (e) => e is NoSuchMethodError)
    *       .then((v) { ... });
    *
    * This method is equivalent to:
    *
@@ skipping 282 matching lines @@
   if (replacement != null) {
     error = _nonNullError(replacement.error);
     stackTrace = replacement.stackTrace;
   }
   result._completeError(error, stackTrace);
 }
 
 /** Helper function that converts `null` to a [NullThrownError]. */
 Object _nonNullError(Object error) =>
   (error != null) ? error : new NullThrownError();