Fix more warnings for dart:html.

tools/dom/src/dartium_KeyEvent.dart

Index: tools/dom/src/dartium_KeyEvent.dart
diff --git a/tools/dom/src/dartium_KeyEvent.dart b/tools/dom/src/dartium_KeyEvent.dart
index 830da2f44244062d206ecc3dcceefebbacc66f5e..1e3ff57466e4e40f8358d4ebc110edeed8dd135d 100644
--- a/tools/dom/src/dartium_KeyEvent.dart
+++ b/tools/dom/src/dartium_KeyEvent.dart
@@ -129,4 +129,14 @@ 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();
 }