Move implementation of Range::firstNode and Range::pastLastNode to Position

Source/core/dom/Position.cpp

Index: Source/core/dom/Position.cpp
diff --git a/Source/core/dom/Position.cpp b/Source/core/dom/Position.cpp
index 023359bf78dc21f83061e1a2a402e88f38cd055c..4226e3fefaa930f226bfe18daff66ec23fafe69b 100644
--- a/Source/core/dom/Position.cpp
+++ b/Source/core/dom/Position.cpp
@@ -231,6 +231,14 @@ Position Position::parentAnchoredEquivalent() const
     return Position(containerNode(), computeOffsetInContainerNode(), PositionIsOffsetInAnchor);
 }
 
+Position Position::toOffsetInAnchor() const
+{
+    if (isNull())
+        return Position();
+
+    return Position(containerNode(), computeOffsetInContainerNode(), Position::PositionIsOffsetInAnchor);
+}
+
 Node* Position::computeNodeBeforePosition() const
 {
     if (!m_anchorNode)
@@ -272,6 +280,34 @@ Node* Position::computeNodeAfterPosition() const
     return 0;
 }
 
+// An implementation of |Range::firstNode()|.
+Node* Position::nodeAsRangeFirstNode() const
+{
+    ASSERT(m_anchorType == PositionIsOffsetInAnchor);
+    if (!m_anchorNode)
+        return nullptr;
+    if (m_anchorNode->offsetInCharacters())
+        return m_anchorNode.get();
+    if (Node* child = NodeTraversal::childAt(*m_anchorNode, m_offset))
+        return child;
+    if (!m_offset)
+        return m_anchorNode.get();
+    return NodeTraversal::nextSkippingChildren(*m_anchorNode);
+}
+
+// An implementation of |Range::pastLastNode()|.
+Node* Position::nodeAsRangePastLastNode() const
+{
+    ASSERT(m_anchorType == PositionIsOffsetInAnchor);
+    if (!m_anchorNode)
+        return nullptr;
+    if (m_anchorNode->offsetInCharacters())
+        return NodeTraversal::nextSkippingChildren(*m_anchorNode);
+    if (Node* child = NodeTraversal::childAt(*m_anchorNode, m_offset))
+        return child;
+    return NodeTraversal::nextSkippingChildren(*m_anchorNode);
+}
+
 Position::AnchorType Position::anchorTypeForLegacyEditingPosition(Node* anchorNode, int offset)
 {
     if (anchorNode && editingIgnoresContent(anchorNode)) {