Convert USERSELECT_ALL to a runtime enabled feature.

Source/core/dom/Node.cpp

Index: Source/core/dom/Node.cpp
diff --git a/Source/core/dom/Node.cpp b/Source/core/dom/Node.cpp
index e6df0b1534454c2e2a8cf208f040c85a316b5104..39360244d6c71b9c30c72f0f15c46559cc1c6797 100644
--- a/Source/core/dom/Node.cpp
+++ b/Source/core/dom/Node.cpp
@@ -652,14 +652,10 @@ bool Node::rendererIsEditable(EditableLevel editableLevel, UserSelectAllTreatmen
 
     for (const Node* node = this; node; node = node->parentNode()) {
         if ((node->isHTMLElement() || node->isDocumentNode()) && node->renderer()) {
-#if ENABLE(USERSELECT_ALL)
             // Elements with user-select: all style are considered atomic
             // therefore non editable.
-            if (node->renderer()->style()->userSelect() == SELECT_ALL && treatment == UserSelectAllIsAlwaysNonEditable)
+            if (Position::nodeIsUserSelectAll(node) && treatment == UserSelectAllIsAlwaysNonEditable)
                 return false;
-#else
-            UNUSED_PARAM(treatment);
-#endif
             switch (node->renderer()->style()->userModify()) {
             case READ_ONLY:
                 return false;