Improve parsing/interpretation of consecutive $$ in network filters

Author: gorhill

src/js/static-filtering-parser.js

@@ -1520,18 +1520,20 @@ export class AstFilterParser {
 
     indexOfNetAnchor(s) {
         const end = s.length;
-        if ( end === 0 ) { return end; }
+        if ( end === 0 ) { return 0; }
         let j = s.lastIndexOf('$');
         if ( j === -1 ) { return end; }
-        if ( (j+1) === end ) { return end; }
+        let htmlFilteringRule = false;
         for (;;) {
-            const before = s.charAt(j-1);
-            if ( before === '$' ) { return -1; }
+            if ( s.charCodeAt(j-1) === 0x24 /* $ */ ) {
+                htmlFilteringRule = true;
+            }
             if ( this.reNetOptionTokens.test(s.slice(j+1)) ) { return j; }
             if ( j === 0 ) { break; }
             j = s.lastIndexOf('$', j-1);
             if ( j === -1 ) { break; }
         }
+        if ( htmlFilteringRule ) { return -1; } 
         return end;
     }