Add @Mugen87's simplification to @greggman's PR.

examples/js/controls/OrbitControls.js

@@ -1140,7 +1140,7 @@ THREE.OrbitControls = function ( object, domElement ) {
 
 	// make sure element can receive keys.
 
-	if ( scope.domElement !== document && scope.domElement.tabIndex === -1) {
+	if ( scope.domElement.tabIndex === -1 ) {
 
 		scope.domElement.tabIndex = 0;