[Editing][Regression] Contenteditable w/ "-webkit-user-select:all" should be editable for drag.

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

 /*
  * Copyright (C) 2004, 2005, 2006, 2007 Apple 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
  *    notice, this list of conditions and the following disclaimer.
  * 2. Redistributions in binary form must reproduce the above copyright
  *    notice, this list of conditions and the following disclaimer in the
@@ skipping 800 matching lines @@
     }
     return nullptr;
 }
 
 bool nodeIsUserSelectAll(const Node* node)
 {
     return RuntimeEnabledFeatures::userSelectAllEnabled() && node && node->layoutObject() && node->layoutObject()->style()->userSelect() == SELECT_ALL;
 
 }
 
+EUserSelect usedValueOfUserSelect(const Node& node)
+{
+    if (node.isHTMLElement() && toHTMLElement(node).isTextFormControl())
+        return SELECT_TEXT;
+    if (!node.layoutObject())
+        return SELECT_NONE;
+
+    const ComputedStyle* style = node.layoutObject()->style();
+    if (style->userModify() != READ_ONLY)
+        return SELECT_TEXT;
+
+    return style->userSelect();
+}
+
 template <typename Strategy>
 TextDirection directionOfEnclosingBlockAlgorithm(const PositionTemplate<Strategy>& position)
 {
     Element* enclosingBlockElement = enclosingBlock(PositionTemplate<Strategy>::firstPositionInOrBeforeNode(position.computeContainerNode()), CannotCrossEditingBoundary);
     if (!enclosingBlockElement)
         return LTR;
     LayoutObject* layoutObject = enclosingBlockElement->layoutObject();
     return layoutObject ? layoutObject->style()->direction() : LTR;
 }
 
@@ skipping 985 matching lines @@
 {
     if (!RuntimeEnabledFeatures::inputEventEnabled())
         return DispatchEventResult::NotCanceled;
     if (!target)
         return DispatchEventResult::NotCanceled;
     InputEvent* beforeInputEvent = InputEvent::createBeforeInput(inputType, data, InputEvent::EventCancelable::IsCancelable, InputEvent::EventIsComposing::NotComposing, ranges);
     return target->dispatchEvent(beforeInputEvent);
 }
 
 } // namespace blink