Issue 5201 - [emscripten] Replace EM_ASM calls by a custom JavaScript library

compiled/subscription/DownloadableSubscription.h

 /*
  * This file is part of Adblock Plus <https://adblockplus.org/>,
  * Copyright (C) 2006-2017 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
  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  * GNU General Public License for more details.
  *
  * You should have received a copy of the GNU General Public License
  * along with Adblock Plus.  If not, see <http://www.gnu.org/licenses/>.
  */
 
 #pragma once
 
+#include <emscripten.h>
+
 #include "Subscription.h"
 
 class DownloadableSubscription : public Subscription
 {
 public:
   explicit DownloadableSubscription(const String& id);
 
   SUBSCRIPTION_PROPERTY(bool, mFixedTitle, SUBSCRIPTION_FIXEDTITLE,
       GetFixedTitle, SetFixedTitle);
   SUBSCRIPTION_STRING_PROPERTY(mHomepage, SUBSCRIPTION_HOMEPAGE,
@@ skipping 14 matching lines @@
       GetErrorCount, SetErrorCount);
   SUBSCRIPTION_PROPERTY(uint64_t, mDataRevision, NONE,
       GetDataRevision, SetDataRevision);
   SUBSCRIPTION_STRING_PROPERTY(mRequiredVersion, NONE,
       GetRequiredVersion, SetRequiredVersion);
   SUBSCRIPTION_PROPERTY(int, mDownloadCount, NONE,
       GetDownloadCount, SetDownloadCount);
 
   EMSCRIPTEN_KEEPALIVE OwnedString Serialize() const;
 };