JS: Fix possible typo in DominatingPaths::hasWrite

Should most likely refer to `AccessPathWrite` and look for write nodes.
This also improves the performance of `rankedAccessPath`, since the
set of candidate blocks is now limited to blocks with both a read and a write.

javascript/ql/lib/semmle/javascript/GlobalAccessPaths.qll

@@ -492,7 +492,7 @@ module AccessPath {
      */
     pragma[noinline]
     private predicate hasWrite(ReachableBasicBlock bb) {
-      bb = getAccessTo(_, _, AccessPathRead()).getBasicBlock()
+      bb = getAccessTo(_, _, AccessPathWrite()).getBasicBlock()
     }
 
     /**