Introduce composed tree version of directionOfEnclosingBlock()

Source/core/editing/EditingUtilities.cpp

Index: Source/core/editing/EditingUtilities.cpp
diff --git a/Source/core/editing/EditingUtilities.cpp b/Source/core/editing/EditingUtilities.cpp
index 24dc578225bebd0fab33b54f51ab60d72ce62135..10e9586950e1d05fd1d47f36e3fcf9a4bd09b1c0 100644
--- a/Source/core/editing/EditingUtilities.cpp
+++ b/Source/core/editing/EditingUtilities.cpp
@@ -693,15 +693,26 @@ bool nodeIsUserSelectNone(Node* node)
     return node && node->layoutObject() && !node->layoutObject()->isSelectable();
 }
 
-TextDirection directionOfEnclosingBlock(const Position& position)
+template <typename Strategy>
+TextDirection directionOfEnclosingBlockAlgorithm(const PositionAlgorithm<Strategy>& position)
 {
-    Element* enclosingBlockElement = enclosingBlock(position.computeContainerNode());

[yoichio, 2015/08/28 05:55:23]

enclosingBlock has DOM/InComposition overrides so why do you code just like 
|enclosingBlock(position)| ?

[yosin_UTC9, 2015/08/28 06:22:58]

PS#1 does |enclosingBlock(position)|, however as you said in comment:

enclosingBlock(position.computeContainerNode())
== enclosingBlock(firstPositionInOrBeforeNode(position.computeContainerNode())

So, PS#2 passes
PositionAlgorithm<Strategy>::firstPositionInOrBeforeNode(position.computeContainerNode())

+    Element* enclosingBlockElement = enclosingBlock(PositionAlgorithm<Strategy>::firstPositionInOrBeforeNode(position.computeContainerNode()), CannotCrossEditingBoundary);
     if (!enclosingBlockElement)
         return LTR;
     LayoutObject* layoutObject = enclosingBlockElement->layoutObject();
     return layoutObject ? layoutObject->style()->direction() : LTR;
 }
 
+TextDirection directionOfEnclosingBlock(const Position& position)
+{
+    return directionOfEnclosingBlockAlgorithm<EditingStrategy>(position);
+}
+
+TextDirection directionOfEnclosingBlock(const PositionInComposedTree& position)
+{
+    return directionOfEnclosingBlockAlgorithm<EditingInComposedTreeStrategy>(position);
+}
+
 TextDirection primaryDirectionOf(const Node& node)
 {
     TextDirection primaryDirection = LTR;