Have Position deal with more references

Source/core/editing/FrameSelection.cpp

Index: Source/core/editing/FrameSelection.cpp
diff --git a/Source/core/editing/FrameSelection.cpp b/Source/core/editing/FrameSelection.cpp
index ec3aeb755a65e90c20cc023ad8b498c40e858af2..23ed26c171e1e9047368c79b5a16472e77bd720a 100644
--- a/Source/core/editing/FrameSelection.cpp
+++ b/Source/core/editing/FrameSelection.cpp
@@ -590,7 +590,7 @@ VisiblePosition FrameSelection::nextWordPositionForPlatform(const VisiblePositio
 static void adjustPositionForUserSelectAll(VisiblePosition& pos, bool isForward)
 {
     if (Node* rootUserSelectAll = Position::rootUserSelectAllForNode(pos.deepEquivalent().anchorNode()))
-        pos = VisiblePosition(isForward ? positionAfterNode(rootUserSelectAll).downstream(CanCrossEditingBoundary) : positionBeforeNode(rootUserSelectAll).upstream(CanCrossEditingBoundary));
+        pos = VisiblePosition(isForward ? positionAfterNode(*rootUserSelectAll).downstream(CanCrossEditingBoundary) : positionBeforeNode(*rootUserSelectAll).upstream(CanCrossEditingBoundary));
 }
 
 VisiblePosition FrameSelection::modifyExtendingRight(TextGranularity granularity)