Fixed dnd for tabs

Resolves #6033

Auditors: @bsclifton

Test Plan:
- try dnd tabs as mentioned in #6033

js/dnd.js

@@ -45,7 +45,7 @@ module.exports.onDragOver = (dragType, sourceBoundingRect, draggingOverKey, drag
 
   e.preventDefault()
   e.dataTransfer.dropEffect = 'move'
-  // Otherise, only accept it if we have some frameProps
+  // Otherwise, only accept it if we have some frameProps
   if (!dndData.hasDragData(e.dataTransfer, dragType)) {
     windowActions.setIsBeingDraggedOverDetail(dragType, draggingOverKey, {
       draggingOverLeftHalf: false,

js/dndData.js

@@ -5,7 +5,7 @@
 const Immutable = require('immutable')
 
 module.exports.hasDragData = (dataTransfer, dragType) => {
-  return !!dataTransfer.getData(`application/x-brave-${dragType}`)
+  return dataTransfer.types.includes(`application/x-brave-${dragType}`)
 }
 
 module.exports.getDragData = (dataTransfer, dragType) => {