[CodeHealth] Use Position::anchorNode instead of deprecatedNode.

Source/core/editing/InputMethodController.cpp

Index: Source/core/editing/InputMethodController.cpp
diff --git a/Source/core/editing/InputMethodController.cpp b/Source/core/editing/InputMethodController.cpp
index 8fdbd05dd0bb1bde035c0655bd59b895fb0baf2d..623e95a204963231b23885aad3f3bf1a81ea1643 100644
--- a/Source/core/editing/InputMethodController.cpp
+++ b/Source/core/editing/InputMethodController.cpp
@@ -271,9 +271,9 @@ void InputMethodController::setComposition(const String& text, const Vector<Comp
         // Find out what node has the composition now.
         Position base = frame().selection().base().downstream();
         Position extent = frame().selection().extent();
-        Node* baseNode = base.deprecatedNode();
+        Node* baseNode = base.anchorNode();
         unsigned baseOffset = base.deprecatedEditingOffset();
-        Node* extentNode = extent.deprecatedNode();
+        Node* extentNode = extent.anchorNode();
         unsigned extentOffset = extent.deprecatedEditingOffset();
 
         if (baseNode && baseNode == extentNode && baseNode->isTextNode() && baseOffset + text.length() == extentOffset) {