Updated top level docs for Window.

tools/dom/src/CrossFrameTypes.dart

Index: tools/dom/src/CrossFrameTypes.dart
diff --git a/tools/dom/src/CrossFrameTypes.dart b/tools/dom/src/CrossFrameTypes.dart
index 935383942ea1628ce36550f7f83eab35feae2859..f8ed874334a29cbd60921a902af8010f68d0476a 100644
--- a/tools/dom/src/CrossFrameTypes.dart
+++ b/tools/dom/src/CrossFrameTypes.dart
@@ -5,17 +5,16 @@
 part of html;
 
 /**
- * An object representing the top-level context object for web scripting.
+ * Top-level container for a browser tab or window.
  *
- * In a web browser, a [Window] object represents the actual browser window.
- * In a multi-tabbed browser, each tab has its own [Window] object. A [Window]
- * is the container that displays a [Document]'s content. All web scripting
- * happens within the context of a [Window] object.
+ * In a web browser, a [WindowBase] object represents any browser window.  This
+ * abstract class contains the state of the window and its relation to other
+ * windows, such as which window opened it.
  *
  * **Note:** This class represents any window, whereas [Window] is
- * used to access the properties and content of the current window.
+ * used to access the properties and content of the current window or tab.
  *
- * See also:
+ * ## Other resources
  *
  * * [DOM Window](https://developer.mozilla.org/en-US/docs/DOM/window) from MDN.
  * * [Window](http://www.w3.org/TR/Window/) from the W3C.