Introduce honorEditingBoundaryAtOrBeforeOf() to avoid referencing constructing object

Source/core/editing/VisiblePosition.cpp

Index: Source/core/editing/VisiblePosition.cpp
diff --git a/Source/core/editing/VisiblePosition.cpp b/Source/core/editing/VisiblePosition.cpp
index 046f5b6883f9c9c47e687b62db901d27e73890bd..f840785e4270b900d5906d5e53abfae6b201c7ef 100644
--- a/Source/core/editing/VisiblePosition.cpp
+++ b/Source/core/editing/VisiblePosition.cpp
@@ -450,12 +450,12 @@ VisiblePosition VisiblePosition::right(bool stayInEditableContent) const
     return directionOfEnclosingBlock(right.deepEquivalent()) == LTR ? honorEditingBoundaryAtOrAfter(right) : honorEditingBoundaryAtOrBefore(right);
 }
 
-VisiblePosition VisiblePosition::honorEditingBoundaryAtOrBefore(const VisiblePosition &pos) const
+static VisiblePosition honorEditingBoundaryAtOrBeforeOf(const VisiblePosition& pos, const Position& anchor)
 {
     if (pos.isNull())
         return pos;
 
-    ContainerNode* highestRoot = highestEditableRoot(deepEquivalent());
+    ContainerNode* highestRoot = highestEditableRoot(anchor);
 
     // Return empty position if pos is not somewhere inside the editable region containing this position
     if (highestRoot && !pos.deepEquivalent().deprecatedNode()->isDescendantOf(highestRoot))
@@ -476,6 +476,11 @@ VisiblePosition VisiblePosition::honorEditingBoundaryAtOrBefore(const VisiblePos
     return lastEditableVisiblePositionBeforePositionInRoot(pos.deepEquivalent(), highestRoot);
 }
 
+VisiblePosition VisiblePosition::honorEditingBoundaryAtOrBefore(const VisiblePosition &pos) const
+{
+    return honorEditingBoundaryAtOrBeforeOf(pos, deepEquivalent());
+}
+
 VisiblePosition VisiblePosition::honorEditingBoundaryAtOrAfter(const VisiblePosition &pos) const
 {
     if (pos.isNull())