test($compile): fix test

The fixed test is supposed to test a fix for an IE11 bug/peculiarity that
arises when using a specifically configured MutationObserver on the page
(see angular#11781 for more info).
The configuration contained a typo (`sublist` instead of `subtree`), which
effectively failed to set up the MutationObserver in a way that would make
the IE11 bug appear.

Closes angular#12061

Author: gkalpak

test/ng/compileSpec.js

@@ -2998,7 +2998,7 @@ describe('$compile', function() {
 
       // Create and register the MutationObserver
       var observer = new window.MutationObserver(noop);
-      observer.observe(document.body, {childList: true, sublist: true});
+      observer.observe(document.body, {childList: true, subtree: true});
 
       // Run the actual test
       var base = jqLite('<div>&mdash; {{ "This doesn\'t." }}</div>');