Refactor Future constructors.

tools/dom/templates/html/impl/impl_IDBFactory.darttemplate

 // 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 $LIBRARYNAME;
 
 $(ANNOTATIONS)class $CLASSNAME$EXTENDS$IMPLEMENTS$NATIVESPEC {
   /**
    * Checks to see if Indexed DB is supported on the current platform.
    */
   static bool get supported {
 $if DARTIUM
     return true;
 $else
     return JS('bool',
         '!!(window.indexedDB || '
         'window.webkitIndexedDB || '
         'window.mozIndexedDB)');
 $endif
   }
 
   @DomName('IDBFactory.open')
   Future<Database> open(String name,
       {int version, void onUpgradeNeeded(VersionChangeEvent),
       void onBlocked(Event)}) {
     if ((version == null) != (onUpgradeNeeded == null)) {
-      return new Future.immediateError(new ArgumentError(
+      return new Future.error(new ArgumentError(
           'version and onUpgradeNeeded must be specified together'));
     }
     try {
       var request;
       if (version != null) {
         request = $dom_open(name, version);
       } else {
         request = $dom_open(name);
       }
 
       if (onUpgradeNeeded != null) {
         request.onUpgradeNeeded.listen(onUpgradeNeeded);
       }
       if (onBlocked != null) {
         request.onBlocked.listen(onBlocked);
       }
       return _completeRequest(request);
     } catch (e, stacktrace) {
-      return new Future.immediateError(e, stacktrace);
+      return new Future.error(e, stacktrace);
     }
   }
 
   @DomName('IDBFactory.deleteDatabase')
   Future<IdbFactory> deleteDatabase(String name,
       {void onBlocked(Event)}) {
     try {
       var request = $dom_deleteDatabase(name);
 
       if (onBlocked != null) {
         request.onBlocked.listen(onBlocked);
       }
       return _completeRequest(request);
     } catch (e, stacktrace) {
-      return new Future.immediateError(e, stacktrace);
+      return new Future.error(e, stacktrace);
     }
   }
 
   @DomName('IDBFactory.getDatabaseNames')
   @SupportedBrowser(SupportedBrowser.CHROME)
   @Experimental
   Future<List<String>> getDatabaseNames() {
     try {
       var request = $dom_webkitGetDatabaseNames();
 
       return _completeRequest(request);
     } catch (e, stacktrace) {
-      return new Future.immediateError(e, stacktrace);
+      return new Future.error(e, stacktrace);
     }
   }
 
   /**
    * Checks to see if getDatabaseNames is supported by the current platform.
    */
   bool get supportsDatabaseNames {
 $if DART2JS
     return supported && JS('bool',
         '!!(#.getDatabaseNames || #.webkitGetDatabaseNames)', this, this);
@@ skipping 15 matching lines @@
   // TODO: make sure that completer.complete is synchronous as transactions
   // may be committed if the result is not processed immediately.
   request.onSuccess.listen((e) {
     completer.complete(request.result);
   });
   request.onError.listen((e) {
     completer.completeError(e);
   });
   return completer.future;
 }