Added some more documentation to top level Window.

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 b218ef9311ab8be8c32783913e9f777491024bcd..7b4442d53dc7e8e33d25c6e146da6a9662da1fab 100644
--- a/sdk/lib/html/dart2js/html_dart2js.dart
+++ b/sdk/lib/html/dart2js/html_dart2js.dart
@@ -38,12 +38,22 @@ import 'dart:_foreign_helper' show JS;
 
 
 /**
- * The top-level Window object.
+ * Top-level container for a web page, which is usually a browser tab or window.
+ *
+ * Each web page loaded in the browser has its own [Window], which is a
+ * container for the web page.
+ *
+ * If the web page has any `<iframe>` elements, then each `iframe` has its own

[Kathy Walrath, 2013/07/11 22:59:45]

I would use either iframe or `<iframe>` (never `iframe`), but otherwise lgtm.

+ * [Window] object, which is accessible only to that `iframe`.
+ *
+ * See also:
+ *
+ *   * [Window](https://developer.mozilla.org/en-US/docs/Web/API/window) from MDN.
  */
 Window get window => JS('Window', 'window');
 
 /**
- * The top-level Document object.
+ * Root node for all content in a web page.
  */
 HtmlDocument get document => JS('HtmlDocument', 'document');