Fix not properly resetting needle buffer in createTrieFromStoredDomainOpt()

Related issue:
- https://github.com/uBlockOrigin/uBlock-issues/issues/1902

The cached needle didn't match the one stored in the
needle buffer when resetting the cached needle without
resetting the needle buffer.

src/js/hntrie.js

@@ -266,7 +266,8 @@ class HNTrieContainer {
                 this.add(itrie);
             }
         }
-        this.needle = ''; // Important
+        this.needle = '';   // Important
+        this.buf[255] = 0;  // Important
         return itrie;
     }