Issue 6592 - Implement $rewrite filter option

test/filterClasses.js

 /*
  * This file is part of Adblock Plus <https://adblockplus.org/>,
  * Copyright (C) 2006-present eyeo GmbH
  *
  * Adblock Plus is free software: you can redistribute it and/or modify
  * it under the terms of the GNU General Public License version 3 as
  * published by the Free Software Foundation.
  *
  * Adblock Plus is distributed in the hope that it will be useful,
  * but WITHOUT ANY WARRANTY; without even the implied warranty of
@@ skipping 502 matching lines @@
   let filter = Filter.fromText(text);
 
   test.equal(filter.rewrite, "$1");
   // no rewrite occured: didn't match.
   test.equal(filter.rewriteUrl("foo"), "foo");
   // rewrite occured: matched.
   test.equal(filter.rewriteUrl("http://content.server/file/foo.txt?bar"),
              "http://content.server/file/foo.txt");
 
   // checking for same origin.
-  let rewriteDiffOrigin = "/content\\.server(\\/file\\/.*\\.txt)\\?.*$/$rewrite=foo.com$1";
+  let rewriteDiffOrigin =
+      "/content\\.server(\\/file\\/.*\\.txt)\\?.*$/$rewrite=foo.com$1";
   let filterDiffOrigin = Filter.fromText(rewriteDiffOrigin);
 
   // no rewrite occured because of a different origin.
   test.equal(
     filterDiffOrigin.rewriteUrl("http://content.server/file/foo.txt?bar"),
-    "http://content.server/file/foo.txt?bar");
-
-  test.done();
-};
+    "http://content.server/file/foo.txt?bar"
+  );
+
+  // relative path.
+  let rewriteRelative = "/(\\/file\\/.*\\.txt)\\?.*$/$rewrite=$1/disable";
+  let filterRelative = Filter.fromText(rewriteRelative);
+
+  test.equal(
+    filterRelative.rewriteUrl("http://content.server/file/foo.txt?bar"),
+    "http://content.server/file/foo.txt/disable"
+  );
+  test.equal(
+    filterRelative.rewriteUrl("http://example.com/file/foo.txt?bar"),
+    "http://example.com/file/foo.txt/disable"
+  );
+
+  test.done();
+};