DevTools: Add support for adding folders to workspace with drag and drop (renderer part)

Source/devtools/front_end/InspectorFrontendHostStub.js

Index: Source/devtools/front_end/InspectorFrontendHostStub.js
diff --git a/Source/devtools/front_end/InspectorFrontendHostStub.js b/Source/devtools/front_end/InspectorFrontendHostStub.js
index 11c258ab71684bc8552b239b4242aa325f18bd8b..13edfa7b5c41fa38ca6c6a66f667f3dd58942b95 100644
--- a/Source/devtools/front_end/InspectorFrontendHostStub.js
+++ b/Source/devtools/front_end/InspectorFrontendHostStub.js
@@ -174,6 +174,10 @@ WebInspector.InspectorFrontendHostStub.prototype = {
         return null;
     },
 
+    upgradeDraggedFileSystemPermissions: function(domFileSystem)
+    {
+    },
+
     indexPath: function(requestId, fileSystemPath)
     {
     },