Add support for AdGuard's mp4 filter option

Related discussion:
- uBlockOrigin/uBlock-issues#701 (comment)

The `mp4` filter option will be converted to `redirect=noopmp4-1s`
internally, and `media` type will be assumed.

src/js/redirect-engine.js

@@ -273,7 +273,6 @@ const RedirectEngine = function() {
 
 RedirectEngine.prototype.reset = function() {
  this.rules = new Map();
- this.ruleTypes = new Set();
  this.ruleSources = new Set();
  this.ruleDestinations = new Set();
  this.modifyTime = Date.now();
@@ -384,7 +383,6 @@ RedirectEngine.prototype.toURL = function(fctxt) {
 RedirectEngine.prototype.addRule = function(src, des, type, pattern, redirect) {
  this.ruleSources.add(src);
  this.ruleDestinations.add(des);
- this.ruleTypes.add(type);
  const key = `${src} ${des} ${type}`,
  entries = this.rules.get(key);
  if ( entries === undefined ) {
@@ -475,6 +473,10 @@ RedirectEngine.prototype.compileRuleFromStaticFilter = function(line) {
  redirect = 'empty';
  continue;
  }
+ if ( option === 'mp4' ) {
+ redirect = 'noopmp4-1s';
+ continue;
+ }
  if ( option.startsWith('domain=') ) {
  srchns = option.slice(7).split('|');
  continue;
@@ -496,8 +498,13 @@ RedirectEngine.prototype.compileRuleFromStaticFilter = function(line) {
 
  // Need one single type -- not negated.
  if ( type === undefined ) {
- if ( redirect !== 'empty' ) { return; }
- type = '*';
+ if ( redirect === 'empty' ) {
+ type = '*';
+ } else if ( redirect === 'noopmp4-1s' ) {
+ type = 'media';
+ } else {
+ return;
+ }
  }
 
  if ( deshn === '' ) {
@@ -562,7 +569,6 @@ RedirectEngine.prototype.toSelfie = function(path) {
  `${path}/main`,
  JSON.stringify({
  rules: rules,
- ruleTypes: Array.from(this.ruleTypes),
  ruleSources: Array.from(this.ruleSources),
  ruleDestinations: Array.from(this.ruleDestinations)
  })
@@ -580,7 +586,6 @@ RedirectEngine.prototype.fromSelfie = function(path) {
  }
  if ( selfie instanceof Object === false ) { return false; }
  this.rules = new Map(selfie.rules);
- this.ruleTypes = new Set(selfie.ruleTypes);
  this.ruleSources = new Set(selfie.ruleSources);
  this.ruleDestinations = new Set(selfie.ruleDestinations);
  this.modifyTime = Date.now();

src/js/static-net-filtering.js

@@ -2011,7 +2011,7 @@ FilterParser.prototype.parseOptions = function(s) {
  continue;
  }
  // Used by Adguard, purpose is unclear -- just ignore for now.
- if ( opt === 'empty' ) {
+ if ( opt === 'empty' || opt === 'mp4' ) {
  if ( this.redirect !== 0 ) {
  this.unsupported = true;
  break;