DevTools: fix DOM multiline editing, extract multiline editor API.

Source/devtools/front_end/elements/ElementsTreeOutline.js

 /*
  * Copyright (C) 2007, 2008 Apple Inc.  All rights reserved.
  * Copyright (C) 2008 Matt Lilek <webkit@mattlilek.com>
  * Copyright (C) 2009 Joseph Pecoraro
  *
  * 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 1934 matching lines @@
                 child = child.nextSibling;
             }
 
             this.treeOutline.childrenListElement.parentElement.removeEventListener("mousedown", consume, false);
             this.updateSelection();
             this.treeOutline.element.focus();
         }
 
         var config = new WebInspector.InplaceEditor.Config(commit.bind(this), dispose.bind(this));
         config.setMultilineOptions(initialValue, { name: "xml", htmlMode: true }, "web-inspector-html", WebInspector.settings.domWordWrap.get(), true);
-        self.runtime.instancePromise(WebInspector.InplaceEditor).then(markAsBeingEdited.bind(this)).done();
+        WebInspector.InplaceEditor.startMultilineEditing(this._htmlEditElement, config).then(markAsBeingEdited.bind(this)).done();
 
         /**
-         * @param {!WebInspector.InplaceEditor} inplaceEditor
+         * @param {!Object} controller
          * @this {WebInspector.ElementsTreeElement}
          */
-        function markAsBeingEdited(inplaceEditor)
+        function markAsBeingEdited(controller)
         {
-            this._editing = /** @type {!WebInspector.InplaceEditor} */ (inplaceEditor).startEditing(this._htmlEditElement, config);
+            this._editing = /** @type {!WebInspector.InplaceEditor.Controller} */ (controller);
             this._editing.setWidth(this.treeOutline._visibleWidth);
             this.treeOutline._multilineEditing = this._editing;
         }
     },
 
     _attributeEditingCommitted: function(element, newText, oldText, attributeName, moveDirection)
     {
         delete this._editing;
 
         var treeOutline = this.treeOutline;
@@ skipping 970 matching lines @@
                 treeOutline.element.classList.add("outline-disclosure");
                 if (!treeOutline.children[0].hasChildren)
                     treeOutline.element.classList.add("single-node");
                 treeOutline.setVisible(true);
                 treeOutline.element.treeElementForTest = treeOutline.children[0];
                 resolve(treeOutline.element);
             }
         }
     }
 }