Bug 1303802 - reenable rootNode test chunk now that we don't have a rootNode implementation so the rootNode test which failed when we had one now passes when we don't have one

MozReview-Commit-ID: 45C8gxzo8p3

testing/web-platform/meta/dom/historical.html.ini

@@ -12,10 +12,6 @@
     expected: FAIL
     bug: 660660
 
-  [Node member must be nuked: rootNode]
-    disabled: https://bugzilla.mozilla.org/show_bug.cgi?id=1303802
-    bug: 1269155
-
   [Historical DOM features must be removed: async]
     expected: FAIL