Introduce composed tree version of lastEditableVisiblePositionBeforePositionInRoot()

Source/core/editing/EditingUtilities.h

Index: Source/core/editing/EditingUtilities.h
diff --git a/Source/core/editing/EditingUtilities.h b/Source/core/editing/EditingUtilities.h
index c4b613205c1c6125228db497024f6265f686c890..b49edd4c5fb8f7c761906f581f4b881c3fa140da 100644
--- a/Source/core/editing/EditingUtilities.h
+++ b/Source/core/editing/EditingUtilities.h
@@ -184,9 +184,9 @@ inline Position lastPositionInOrAfterNode(Node* node)
 }
 
 CORE_EXPORT Position firstEditablePositionAfterPositionInRoot(const Position&, Node*);
-Position lastEditablePositionBeforePositionInRoot(const Position&, Node*);
+CORE_EXPORT Position lastEditablePositionBeforePositionInRoot(const Position&, Node*);
 CORE_EXPORT PositionInComposedTree firstEditablePositionAfterPositionInRoot(const PositionInComposedTree&, Node*);
-PositionInComposedTree lastEditablePositionBeforePositionInRoot(const PositionInComposedTree&, Node*);
+CORE_EXPORT PositionInComposedTree lastEditablePositionBeforePositionInRoot(const PositionInComposedTree&, Node*);
 
 // Move up or down the DOM by one position.
 // Offsets are computed using layout text for nodes that have layoutObjects -
@@ -242,7 +242,8 @@ void updatePositionForNodeRemoval(Position&, Node&);
 // specified position due by canonicalization.
 CORE_EXPORT VisiblePosition firstEditableVisiblePositionAfterPositionInRoot(const Position&, ContainerNode*);
 CORE_EXPORT VisiblePositionInComposedTree firstEditableVisiblePositionAfterPositionInRoot(const PositionInComposedTree&, ContainerNode*);
-VisiblePosition lastEditableVisiblePositionBeforePositionInRoot(const Position&, ContainerNode*);
+CORE_EXPORT VisiblePosition lastEditableVisiblePositionBeforePositionInRoot(const Position&, ContainerNode*);
+CORE_EXPORT VisiblePositionInComposedTree lastEditableVisiblePositionBeforePositionInRoot(const PositionInComposedTree&, ContainerNode*);
 VisiblePosition visiblePositionBeforeNode(Node&);
 VisiblePosition visiblePositionAfterNode(Node&);