CSS: Work around an IE11 fullscreen dimensions bug

Fixes gh-1764
Closes gh-2401

src/css.js

@@ -113,6 +113,17 @@ function getWidthOrHeight( elem, name, extra ) {
 		styles = getStyles( elem ),
 		isBorderBox = jQuery.css( elem, "boxSizing", false, styles ) === "border-box";
 
+	// Support: IE11 only
+	// Fix for edge case in IE 11. See gh-1764
+	if ( document.msFullscreenElement && window.top !== window ) {
+		// Support: IE11 only
+		// Running getBoundingClientRect on a disconnected node
+		// in IE throws an error.
+		if ( elem.getClientRects().length ) {
+			val = Math.round( elem.getBoundingClientRect()[ name ] * 100 );
+		}
+	}
+
 	// Some non-html elements return undefined for offsetWidth, so check for null/undefined
 	// svg - https://bugzilla.mozilla.org/show_bug.cgi?id=649285
 	// MathML - https://bugzilla.mozilla.org/show_bug.cgi?id=491668