sdk/lib/html/dartium/html_dartium.dart

Index: sdk/lib/html/dartium/html_dartium.dart
diff --git a/sdk/lib/html/dartium/html_dartium.dart b/sdk/lib/html/dartium/html_dartium.dart
index dc2d1a11064bc70f868124203568b0f4605dccba..ce11bc1e4866d653352ba74501282b445898e004 100644
--- a/sdk/lib/html/dartium/html_dartium.dart
+++ b/sdk/lib/html/dartium/html_dartium.dart
@@ -24719,12 +24719,17 @@ class Window extends EventTarget implements WindowBase {
   }
 
   /**
-   * Returns a Future that completes just before the window is about to repaint
-   * so the user can draw an animation frame
+   * Returns a Future that completes just before the window is about to 
+   * repaint so the user can draw an animation frame.
    *
    * If you need to later cancel this animation, use [requestAnimationFrame]
    * instead.
    *
+   * The [Future] completes to a timestamp that represents a floating
+   * point value of the number of milliseconds that have elapsed since the page 
+   * started to load (which is also the timestamp at this call to 
+   * animationFrame).
+   *
    * Note: The code that runs when the future completes should call
    * [animationFrame] again for the animation to continue.
    */