Fix more warnings for dart:html.

tools/dom/src/dart2js_KeyEvent.dart

Index: tools/dom/src/dart2js_KeyEvent.dart
diff --git a/tools/dom/src/dart2js_KeyEvent.dart b/tools/dom/src/dart2js_KeyEvent.dart
index 8c7b5fd6d6741f823f565be956fb393f1610d428..ac898e24057cfedc3e27bfc0e832c27d28518e2c 100644
--- a/tools/dom/src/dart2js_KeyEvent.dart
+++ b/tools/dom/src/dart2js_KeyEvent.dart
@@ -210,4 +210,14 @@ 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();
 }