Bug 1480147 - Add [ChromeOnly] Node.flattenedTreeParentNode, r=mrbkap

dom/base/nsINode.cpp

@@ -59,6 +59,7 @@
 #include "nsAtom.h"
 #include "nsIBaseWindow.h"
 #include "nsICategoryManager.h"
+#include "nsIContentInlines.h"
 #include "nsIContentIterator.h"
 #include "nsIControllers.h"
 #include "nsIDocument.h"
@@ -2976,6 +2977,12 @@ nsINode::Localize(JSContext* aCx,
   return promise.forget();
 }
 
+nsINode*
+nsINode::GetFlattenedTreeParentNodeNonInline() const
+{
+  return GetFlattenedTreeParentNode();
+}
+
 NS_IMPL_ISUPPORTS(nsNodeWeakReference,
                   nsIWeakReference)
 

dom/base/nsINode.h

@@ -980,6 +980,8 @@ public:
    */
   inline nsINode* GetFlattenedTreeParentNode() const;
 
+  nsINode* GetFlattenedTreeParentNodeNonInline() const;
+
   /**
    * Like GetFlattenedTreeParentNode, but returns the document for any native
    * anonymous content that was generated for ancestor frames of the document

dom/webidl/Node.webidl

@@ -105,6 +105,8 @@ interface Node : EventTarget {
   readonly attribute URI? baseURIObject;
   [ChromeOnly]
   DOMString generateXPath();
+  [ChromeOnly, Pure, BinaryName="flattenedTreeParentNodeNonInline"]
+  readonly attribute Node? flattenedTreeParentNode;
 
   /**
    * This method provides a fast-path for the Fluent localization system to

toolkit/components/tooltiptext/TooltipTextProvider.js

@@ -122,18 +122,7 @@ TooltipTextProvider.prototype = {
         usedTipElement = tipElement;
       }
 
-      let parent = tipElement.parentNode;
-      if (defView.ShadowRoot &&
-          parent instanceof defView.ShadowRoot) {
-        tipElement = parent.host;
-      } else {
-        let slot = tipElement.openOrClosedAssignedSlot;
-        if (slot) {
-          tipElement = slot;
-        } else {
-          tipElement = parent;
-        }
-      }
+      tipElement = tipElement.flattenedTreeParentNode;
     }
 
     return [titleText, XLinkTitleText, SVGTitleText, XULtooltiptextText].some(function(t) {