Fine tune network filter option anchor detection

The change allows to better parse AdGuard filters with `replace=`
option when the value to the `replace=` option contains dollar
sign character `$`. uBO will still reject these filters but will
better identify which dollar sign `$` is the real filter option
anchor.

src/js/static-filtering-parser.js

@@ -1387,9 +1387,17 @@ export class AstFilterParser {
  if ( j === -1 ) { return end; }
  if ( (j+1) === end ) { return end; }
  for (;;) {
- if ( j !== start && s.charCodeAt(j-1) === 0x24 /* $ */ ) { return -1; }
- const c = s.charCodeAt(j+1);
- if ( c !== 0x29 /* ) */ && c !== 0x2F /* / */ && c !== 0x7C /* | */ ) { return j; }
+ const before = s.charCodeAt(j-1);
+ if ( j !== start && before === 0x24 /* $ */ ) { return -1; }
+ const after = s.charCodeAt(j+1);
+ if (
+ after !== 0x29 /* ) */ &&
+ after !== 0x2F /* / */ &&
+ after !== 0x7C /* | */ &&
+ before !== 0x5C /* \ */
+ ) {
+ return j;
+ }
  if ( j <= start ) { break; }
  j = s.lastIndexOf('$', j-1);
  if ( j === -1 ) { break; }