Issue 4136 - Support Chrome's dark devtools theme

devtools-panel.js

 /*
  * This file is part of Adblock Plus <https://adblockplus.org/>,
  * Copyright (C) 2006-2016 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 151 matching lines @@
         row.parentNode.removeChild(row);
         container.classList.add("has-changes");
         break;
 
       case "reset":
         table.innerHTML = "";
         container.classList.remove("has-changes");
         break;
     }
   });
+
+  // Since Chrome 54 the themeName is accessible, for earlier versions we must
+  // assume the default theme is being used.
+  // https://bugs.chromium.org/p/chromium/issues/detail?id=608869
+  let theme = chrome.devtools.panels.themeName || "default";
+  document.body.classList.add(theme);
 }, false);