draggable=true elements should drag even if shift-key is pressed

third_party/WebKit/Source/core/editing/SelectionController.cpp

 /*
  * Copyright (C) 2006, 2007, 2008, 2009, 2010, 2011 Apple Inc. All rights reserved.
  * Copyright (C) 2006 Alexey Proskuryakov (ap@webkit.org)
  * Copyright (C) 2012 Digia Plc. and/or its subsidiary(-ies)
  * Copyright (C) 2015 Google Inc. All rights reserved.
  *
  * 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
@@ skipping 803 matching lines @@
 
 FrameSelection& SelectionController::selection() const {
   return m_frame->selection();
 }
 
 bool isLinkSelection(const MouseEventWithHitTestResults& event) {
   return event.event().altKey() && event.isOverLink();
 }
 
 bool isExtendingSelection(const MouseEventWithHitTestResults& event) {
+  bool isDraggable = false;
+  Node* innerNode = event.innerNode();
+  if (LayoutObject* layoutObject = innerNode->layoutObject()) {
+    const ComputedStyle& style = layoutObject->styleRef();
+    if (style.userDrag() == DRAG_ELEMENT)
+      isDraggable = true;
+  }
+
   bool isMouseDownOnLinkOrImage =
       event.isOverLink() || event.hitTestResult().image();
-  return event.event().shiftKey() && !isMouseDownOnLinkOrImage;
+  return event.event().shiftKey() && !isMouseDownOnLinkOrImage && !isDraggable;
 }
 
 }  // namespace blink