Selector: Throw on post-comma invalid selectors in Opera 10-11 again

PR jquerygh-456 introduced a test catching not throwing on badly-escaped identifiers
by Firefox 3.6-5. Unfortunately, it was placed just before a test Opera 10-11
fails, making Opera fail quicker and not adding a post-comma invalid selector
to rbuggyQSA.

This commit fixes the regression & introduces a unit test ensuring the throwing.
Unfortunately, the issue is fixed in Opera 11.6 which is the lowest one Sizzle
officially supports but I verified the fix manually against Opera 10.6, 11.1
& 11.5.

Ref jquerygh-456

dist/sizzle.js

@@ -6,7 +6,7 @@
  * Released under the MIT license
  * https://js.foundation/
  *
- * Date: 2019-10-13
+ * Date: 2019-10-16
  */
 ( function( window ) {
 var i,
@@ -840,6 +840,11 @@ setDocument = Sizzle.setDocument = function( node ) {
 			if ( !el.querySelectorAll( "a#" + expando + "+*" ).length ) {
 				rbuggyQSA.push( ".#.+[+~]" );
 			}
+
+			// Support: Firefox <=3.6 - 5 only
+			// Old Firefox doesn't throw on a badly-escaped identifier.
+			el.querySelectorAll( "\\\f" );
+			rbuggyQSA.push( "[\\r\\n\\f]" );
 		} );
 
 		assert( function( el ) {
@@ -871,11 +876,6 @@ setDocument = Sizzle.setDocument = function( node ) {
 				rbuggyQSA.push( ":enabled", ":disabled" );
 			}
 
-			// Support: Firefox <=3.6 - 5 only
-			// Old Firefox doesn't throw on a badly-escaped identifier.
-			el.querySelectorAll( "\\\f" );
-			rbuggyQSA.push( "[\\r\\n\\f]" );
-
 			// Support: Opera 10 - 11 only
 			// Opera 10-11 does not throw on post-comma invalid pseudos
 			el.querySelectorAll( "*,:x" );