Revert of [Editing][CSS] Drag from a -webkit-user-select:none element should not start selection

third_party/WebKit/Source/core/dom/Node.cpp

 /*
  * Copyright (C) 1999 Lars Knoll (knoll@kde.org)
  *           (C) 1999 Antti Koivisto (koivisto@kde.org)
  *           (C) 2001 Dirk Mueller (mueller@kde.org)
  * Copyright (C) 2004, 2005, 2006, 2007, 2008, 2009, 2010, 2011 Apple Inc. All rights reserved.
  * Copyright (C) 2008 Nokia Corporation and/or its subsidiary(-ies)
  * Copyright (C) 2009 Torch Mobile Inc. All rights reserved. (http://www.torchmobile.com/)
  *
  * This library is free software; you can redistribute it and/or
  * modify it under the terms of the GNU Library General Public
@@ skipping 955 matching lines @@
 
 // FIXME: Shouldn't these functions be in the editing code?  Code that asks questions about HTML in the core DOM class
 // is obviously misplaced.
 bool Node::canStartSelection() const
 {
     if (hasEditableStyle())
         return true;
 
     if (layoutObject()) {
         const ComputedStyle& style = layoutObject()->styleRef();
-        // We don't allow selections to begin within an element that has
-        // -webkit-user-select: none set,
-        // https://drafts.csswg.org/css-ui-4/#valdef-user-select-none
-        if (style.userSelect() == SELECT_NONE)
+        // We allow selections to begin within an element that has -webkit-user-select: none set,
+        // but if the element is draggable then dragging should take priority over selection.
+        if (style.userDrag() == DRAG_ELEMENT && style.userSelect() == SELECT_NONE)
             return false;
     }
     ContainerNode* parent = FlatTreeTraversal::parent(*this);
     return parent ? parent->canStartSelection() : true;
 }
 
 bool Node::canParticipateInFlatTree() const
 {
     return !isShadowRoot() && !isSlotOrActiveInsertionPoint();
 }
@@ skipping 1485 matching lines @@
 
 void showNodePath(const blink::Node* node)
 {
     if (node)
         node->showNodePathForThis();
     else
         fprintf(stderr, "Cannot showNodePath for (nil)\n");
 }
 
 #endif