Update core visual test to allow testing while the window is scrolled.

Author: David Murdoch

tests/visual/position/position.html

@@ -35,7 +35,7 @@
 	<style>
 		input, .ui-menu { position: absolute; }
 		.ui-menu { width: 200px; }
-		html, body { width: 99%; height: 99% }
+		html, body { width: 99%; height: 99%; min-height:700px; min-width:700px; }
 		#container { width: 95%; height: 95%; border: 1px solid black; margin: auto; }
 	</style>
 </head>