Let input tag filter out non-native files in dropped data.

Source/core/page/DragController.cpp

 /*
  * Copyright (C) 2007, 2009, 2010 Apple Inc. All rights reserved.
  * Copyright (C) 2008 Google Inc.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  * 1. Redistributions of source code must retain the above copyright
  *    notice, this list of conditions and the following disclaimer.
  * 2. Redistributions in binary form must reproduce the above copyright
@@ skipping 367 matching lines @@
         }
 
         if (!m_fileInputElementUnderMouse)
             m_page->dragCaretController().setCaretPosition(m_documentUnderMouse->frame()->visiblePositionForPoint(point));
 
         LocalFrame* innerFrame = element->document().frame();
         dragSession.operation = dragIsMove(innerFrame->selection(), dragData) ? DragOperationMove : DragOperationCopy;
         dragSession.mouseIsOverFileInput = m_fileInputElementUnderMouse;
         dragSession.numberOfItemsToBeAccepted = 0;
 
-        unsigned numberOfFiles = dragData->numberOfFiles();
+        Vector<String> paths;
+        dragData->asFilePaths(paths);
+        const unsigned numberOfFiles = paths.size();
         if (m_fileInputElementUnderMouse) {
             if (m_fileInputElementUnderMouse->isDisabledFormControl())
                 dragSession.numberOfItemsToBeAccepted = 0;
             else if (m_fileInputElementUnderMouse->multiple())
                 dragSession.numberOfItemsToBeAccepted = numberOfFiles;
-            else if (numberOfFiles > 1)
+            else if (numberOfFiles == 1)
+                dragSession.numberOfItemsToBeAccepted = 1;
+            else
                 dragSession.numberOfItemsToBeAccepted = 0;
-            else
-                dragSession.numberOfItemsToBeAccepted = 1;
 
             if (!dragSession.numberOfItemsToBeAccepted)
                 dragSession.operation = DragOperationNone;
             m_fileInputElementUnderMouse->setCanReceiveDroppedFiles(dragSession.numberOfItemsToBeAccepted);
         } else {
             // We are not over a file input element. The dragged item(s) will only
             // be loaded into the view the number of dragged items is 1.
             dragSession.numberOfItemsToBeAccepted = numberOfFiles != 1 ? 0 : 1;
         }
 
@@ skipping 576 matching lines @@
 
 void DragController::trace(Visitor* visitor)
 {
     visitor->trace(m_page);
     visitor->trace(m_documentUnderMouse);
     visitor->trace(m_dragInitiator);
     visitor->trace(m_fileInputElementUnderMouse);
 }
 
 } // namespace blink