Fixed a lot of dartanalyzer static analysis issues with the html lib.

tests/html/keyboard_event_test.dart

Index: tests/html/keyboard_event_test.dart
diff --git a/tests/html/keyboard_event_test.dart b/tests/html/keyboard_event_test.dart
index 4f32f2dd1958523c851b4836dfd4b611d890a83e..20994ed0591c7b15ad82e8a10f36fba816bab357 100644
--- a/tests/html/keyboard_event_test.dart
+++ b/tests/html/keyboard_event_test.dart
@@ -20,10 +20,12 @@ main() {
     // values (a KeyboardEvent can be "init"-ed but not all the information can
     // be programmatically populated. It exists as an example for how to use
     // KeyboardEventController more than anything else.
-    var controller = new KeyboardEventController.keydown(document.window);
+    var controller = new KeyboardEventController.keydown(
+        document.query('body'));
     var func = keydownHandlerTest;
     controller.add(func);
-    document.window.on.keyDown.add((e) => print('regular listener'), false);
+    document.query('body').on.keyDown.add(
+        (e) => print('regular listener'), false);
   });
 }