Issue 5161 - Use maps and sets where appropriate

ext/background.js

 /*
  * 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
@@ skipping 533 matching lines @@
     tabs.forEach(tab =>
     {
       chrome.webNavigation.getAllFrames({tabId: tab.id}, details =>
       {
         if (details && details.length > 0)
         {
           let frames = new Map();
           framesOfTabs.set(tab.id, frames);
 
           for (let detail of details)
-            frames.set(detail.frameId, {url: new URL(detail.url)});
-
-          for (let detail of details)
           {
-            let {parentFrameId} = detail;
-
-            if (parentFrameId != -1)
-              frames.get(detail.frameId).parent = frames.get(parentFrameId);
+            let frame = {url: new URL(detail.url)};
+            frames.set(detail.frameId, frame);
+
+            if (detail.parentFrameId != -1)
+              frame.parent = frames.get(detail.parentFrameId);
           }
         }
       });
     });
   });
 
   chrome.webRequest.onBeforeRequest.addListener(details =>
   {
     // The high-level code isn't interested in requests that aren't
     // related to a tab or requests loading a top-level document,
@@ skipping 160 matching lines @@
   ext.windows = {
     create(createData, callback)
     {
       chrome.windows.create(createData, createdWindow =>
       {
         afterTabLoaded(callback)(createdWindow.tabs[0]);
       });
     }
   };
 }());