Fixed #4 - Disable rewrite option for all but internal redirect

lib/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 724 matching lines @@
     // catch syntax errors
     let regexp = new RegExp(regexpSource.substr(1, regexpSource.length - 2),
                             this.matchCase ? "" : "i");
     Object.defineProperty(this, "regexp", {value: regexp});
   }
   else
   {
     // Patterns like /foo/bar/* exist so that they are not treated as regular
     // expressions. We drop any superfluous wildcards here so our optimizations
     // can kick in.
-    if (this.rewrite)

[Manish Jethani, 2019/04/16 05:52:58]

This actually has a somewhat opposite of the intended effect.

The intention was: If either there is no `$rewrite` or `$rewrite` is
`abp-resource:`, then do this. After the changes here, if there is `$rewrite` it
will always be `abp-resource:`, consequently the check here is redundant now. We
can simply remove the `if` condition.

[hub, 2019/04/16 12:23:06]

Good catch.

-      regexpSource = regexpSource.replace(/^\*+/, "").replace(/\*+$/, "");
+    regexpSource = regexpSource.replace(/^\*+/, "").replace(/\*+$/, "");
 
     if (!this.matchCase && isLiteralPattern(regexpSource))
       regexpSource = regexpSource.toLowerCase();
 
     // No need to convert this filter to regular expression yet, do it on demand
     this.pattern = regexpSource;
   }
 }
 exports.RegExpFilter = RegExpFilter;
 
@@ skipping 71 matching lines @@
     }
 
     Object.defineProperty(
       this, "sitekeys", {value: sitekeys, enumerable: true}
     );
     return this.sitekeys;
   },
 
   /**
    * The name of the internal resource to which to rewrite the
-   * URL. e.g. if the value of the <code>rewrite</code> property is

[Manish Jethani, 2019/04/16 05:52:58]

I think we can replace `<code>rewrite</code> property` with
`<code>$rewrite</code> option` here because otherwise it would be wrong.

[hub, 2019/04/16 12:23:06]

Done.

+   * URL. e.g. if the value of the <code>$rewrite</code> option is
    * <code>abp-resource:blank-html</code>, this should be
    * <code>blank-html</code>.
    * @type {?string}
    */
   rewrite: null,
 
   /**
    * Tests whether the URL matches this filter
    * @param {string} location URL to be tested
    * @param {number} typeMask bitmask of content / request types to match
@@ skipping 188 matching lines @@
             break;
           case "collapse":
             collapse = !inverse;
             break;
           case "sitekey":
             if (!value)
               return new InvalidFilter(origText, "filter_unknown_option");
             sitekeys = value.toUpperCase();
             break;
           case "rewrite":
-            if (!value || !value.startsWith("abp-resource:"))

[Manish Jethani, 2019/04/16 05:52:58]

It doesn't matter _that_ much, but I'd just like to point out that this is an
additional change in behavior. A filter like `foo$rewrite` would given an
"unknown option" error previously, while now it would give a "invalid rewrite"
error. Maybe that's fine.

If we want to stick with the old behavior, then we can leave the check for
`value == null` as it is and check for `!value.startsWith(...)` as an additional
check.

[hub, 2019/04/16 12:23:06]

I think I'm gonna go the safe route. Change was intentional but maybe that's not
a good idea for this fix right now.

+            if (value == null)
+              return new InvalidFilter(origText, "filter_unknown_option");
+            if (!value.startsWith("abp-resource:"))
               return new InvalidFilter(origText, "filter_invalid_rewrite");
             rewrite = value.substr("abp-resource:".length);
             break;
           default:
             return new InvalidFilter(origText, "filter_unknown_option");
         }
       }
     }
   }
 
@@ skipping 341 matching lines @@
 
   /**
    * Script that should be executed
    * @type {string}
    */
   get script()
   {
     return this.body;
   }
 });