Fix more warnings for dart:html.

sdk/lib/html/dart2js/html_dart2js.dart

Index: sdk/lib/html/dart2js/html_dart2js.dart
diff --git a/sdk/lib/html/dart2js/html_dart2js.dart b/sdk/lib/html/dart2js/html_dart2js.dart
index 729b216f68e7bbc080bade8b9a3097590e3d1e1e..aabef473b7a5ff790bc32e994e25a6d86b1410b2 100644
--- a/sdk/lib/html/dart2js/html_dart2js.dart
+++ b/sdk/lib/html/dart2js/html_dart2js.dart
@@ -111,7 +111,7 @@ abstract class _EntryArray implements List<Entry> native "EntryArray" {}
 
 @DocsEditable()
 @DomName('AbstractWorker')
-class AbstractWorker extends Interceptor implements EventTarget native "AbstractWorker" {
+abstract class AbstractWorker extends Interceptor implements EventTarget native "AbstractWorker" {
   // To suppress missing implicit constructor warnings.
   factory AbstractWorker._() { throw new UnsupportedError("Not supported"); }
 
@@ -266,6 +266,12 @@ class AnchorElement extends HtmlElement implements UrlUtils native "HTMLAnchorEl
   @DocsEditable()
   String href;
 
+  @DomName('HTMLAnchorElement.origin')
+  @DocsEditable()
+  // WebKit only
+  @Experimental() // non-standard
+  final String origin;
+
   @DomName('HTMLAnchorElement.password')
   @DocsEditable()
   @Experimental() // untriaged
@@ -7843,16 +7849,19 @@ class DocumentFragment extends Node implements ParentNode native "DocumentFragme
         validator: validator, treeSanitizer: treeSanitizer);
   }
 
+  HtmlCollection get _children => throw new UnimplementedError(
+      'Use _docChildren instead');
+
   // Native field is used only by Dart code so does not lead to instantiation
   // of native classes
   @Creates('Null')
-  List<Element> _children;
+  List<Element> _docChildren;
 
   List<Element> get children {
-    if (_children == null) {
-      _children = new FilteredElementList(this);
+    if (_docChildren == null) {
+      _docChildren = new FilteredElementList(this);
     }
-    return _children;
+    return _docChildren;
   }
 
   void set children(List<Element> value) {
@@ -7988,7 +7997,7 @@ class DocumentFragment extends Node implements ParentNode native "DocumentFragme
 @DomName('DocumentType')
 // http://www.w3.org/TR/DOM-Level-3-Core/core.html#ID-412266927
 @deprecated // stable
-class DocumentType extends Node implements ChildNode native "DocumentType" {
+abstract class DocumentType extends Node implements ChildNode {
   // To suppress missing implicit constructor warnings.
   factory DocumentType._() { throw new UnsupportedError("Not supported"); }
 
@@ -10901,19 +10910,6 @@ abstract class Element extends Node implements GlobalEventHandlers, ParentNode,
   @DocsEditable()
   bool hidden;
 
-  /**
-   * The current state of IME composition.
-   *
-   * ## Other resources
-   *
-   * * [Input method editor specification]
-   * (http://www.w3.org/TR/ime-api/) from W3C.
-   */
-  @DomName('Element.inputMethodContext')
-  @DocsEditable()
-  @Experimental() // untriaged
-  final InputMethodContext inputMethodContext;
-
   @DomName('Element.isContentEditable')
   @DocsEditable()
   final bool isContentEditable;
@@ -29177,6 +29173,15 @@ class _BeforeUnloadEventStreamProvider implements
   String getEventType(EventTarget target) {
     return _eventType;
   }
+
+  ElementStream<BeforeUnloadEvent> forElement(Element e, {bool useCapture: false}) {
+    return new _ElementEventStreamImpl(e, _eventType, useCapture);
+  }
+
+  ElementStream<BeforeUnloadEvent> _forElementList(ElementList e,
+      {bool useCapture: false}) {
+    return new _ElementListEventStreamImpl(e, _eventType, useCapture);
+  }
 }
 // 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
@@ -29206,11 +29211,6 @@ abstract class WindowEventHandlers extends EventTarget {
   // To suppress missing implicit constructor warnings.
   factory WindowEventHandlers._() { throw new UnsupportedError("Not supported"); }
 
-  @DomName('WindowEventHandlers.beforeunloadEvent')
-  @DocsEditable()
-  @Experimental() // untriaged
-  static const EventStreamProvider<Event> beforeUnloadEvent = const EventStreamProvider<Event>('beforeunload');
-
   @DomName('WindowEventHandlers.hashchangeEvent')
   @DocsEditable()
   @Experimental() // untriaged
@@ -29251,11 +29251,6 @@ abstract class WindowEventHandlers extends EventTarget {
   @Experimental() // untriaged
   static const EventStreamProvider<Event> unloadEvent = const EventStreamProvider<Event>('unload');
 
-  @DomName('WindowEventHandlers.onbeforeunload')
-  @DocsEditable()
-  @Experimental() // untriaged
-  Stream<Event> get onBeforeUnload => beforeUnloadEvent.forTarget(this);
-
   @DomName('WindowEventHandlers.onhashchange')
   @DocsEditable()
   @Experimental() // untriaged
@@ -31583,7 +31578,7 @@ abstract class CanvasImageSource {}
  * * [DOM Window](https://developer.mozilla.org/en-US/docs/DOM/window) from MDN.
  * * [Window](http://www.w3.org/TR/Window/) from the W3C.
  */
-abstract class WindowBase implements EventTarget {
+abstract class WindowBase {
   // Fields.
 
   /**
@@ -32656,6 +32651,8 @@ class _CustomEventStreamProvider<T extends Event>
   String getEventType(EventTarget target) {
     return _eventTypeGetter(target);
   }
+
+  String get _eventType => throw new UnsupportedError('Access type through getEventType method.');
 }
 // DO NOT EDIT- this file is generated from running tool/generator.sh.
 
@@ -34890,6 +34887,10 @@ abstract class ReadyState {
  */
 class _WrappedEvent implements Event {
   final Event wrapped;
+
+  /** The CSS selector involved with event delegation. */
+  String _selector;
+
   _WrappedEvent(this.wrapped);
 
   bool get bubbles => wrapped.bubbles;
@@ -34927,6 +34928,39 @@ class _WrappedEvent implements Event {
   void stopPropagation() {
     wrapped.stopPropagation();
   }
+
+  /**
+   * A pointer to the element whose CSS selector matched within which an event
+   * was fired. If this Event was not associated with any Event delegation,
+   * accessing this value will throw an [UnsupportedError].
+   */
+  Element get matchingTarget {
+    if (_selector == null) {
+      throw new UnsupportedError('Cannot call matchingTarget if this Event did'
+          ' not arise as a result of event delegation.');
+    }
+    var currentTarget = this.currentTarget;
+    var target = this.target;
+    var matchedTarget;
+    do {
+      if (target.matches(_selector)) return target;
+      target = target.parent;
+    } while (target != null && target != currentTarget.parent);
+    throw new StateError('No selector matched for populating matchedTarget.');
+  }
+
+  /**
+   * This event's path, taking into account shadow DOM.
+   *
+   * ## Other resources
+   *
+   * * [Shadow DOM extensions to Event]
+   * (http://w3c.github.io/webcomponents/spec/shadow/#extensions-to-event) from
+   * W3C.
+   */
+  // https://dvcs.w3.org/hg/webcomponents/raw-file/tip/spec/shadow/index.html#extensions-to-event
+  @Experimental()
+  List<Node> get path => wrapped.path;
 }
 // Copyright (c) 2013, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
@@ -35580,6 +35614,16 @@ class KeyEvent extends _WrappedEvent implements KeyboardEvent {
     throw new UnsupportedError(
         "Cannot initialize a KeyboardEvent from a KeyEvent.");
   }
+  int get _layerX => throw new UnsupportedError('Not applicable to KeyEvent');
+  int get _layerY => throw new UnsupportedError('Not applicable to KeyEvent');
+  int get _pageX => throw new UnsupportedError('Not applicable to KeyEvent');
+  int get _pageY => throw new UnsupportedError('Not applicable to KeyEvent');
+  @Experimental() // untriaged
+  bool getModifierState(String keyArgument) => throw new UnimplementedError();
+  @Experimental() // untriaged
+  int get location => throw new UnimplementedError();
+  @Experimental() // untriaged
+  bool get repeat => throw new UnimplementedError();
 }
 // Copyright (c) 2011, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a