Add Visual Viewport API

src/Webapi/Dom/Webapi__Dom__VisualViewport.res

@@ -0,0 +1,15 @@
+/// Support for https://developer.mozilla.org/en-US/docs/Web/API/VisualViewport
+
+type t
+
+@get external height: t => int = "height"
+@get external width: t => int = "width"
+@get external scale: t => float = "scale"
+@get external offsetLeft: t => int = "offsetLeft"
+@get external offsetTop: t => int = "offsetTop"
+@get external pageLeft: t => int = "pageLeft"
+@get external pageTop: t => int = "pageTop"
+
+include Webapi__Dom__EventTarget.Impl({
+  type t = t
+})

src/Webapi/Dom/Webapi__Dom__Window.res

@@ -146,6 +146,9 @@ module Impl = (
   @set
   external setOnLoad: (t_window, unit => unit) => unit =
     "onload" /* use addEventListener instead? */
+
+  /* VisualViewport API */
+  @get external visualViewport: t_window => Webapi__Dom__VisualViewport.t = "visualViewport"
 }
 
 type t = Dom.window