Revert NotImplemented() changes in r383029 and r383047.

third_party/WebKit/Source/core/editing/Position.h

Index: third_party/WebKit/Source/core/editing/Position.h
diff --git a/third_party/WebKit/Source/core/editing/Position.h b/third_party/WebKit/Source/core/editing/Position.h
index 9c01ae00154a62898370a1cf393692f412d60e5d..aecc66728462f134eee29e5493630342004b04db 100644
--- a/third_party/WebKit/Source/core/editing/Position.h
+++ b/third_party/WebKit/Source/core/editing/Position.h
@@ -392,6 +392,9 @@ inline PositionInFlatTree fromPositionInDOMTree<EditingInFlatTreeStrategy>(const
 
 // These printers are available only for testing in "webkit_unit_tests", and
 // implemented in "core/testing/CoreTestPrinters.cpp".
+std::ostream& operator<<(std::ostream&, const Node&);
+std::ostream& operator<<(std::ostream&, const Node*);
+
 std::ostream& operator<<(std::ostream&, PositionAnchorType);
 std::ostream& operator<<(std::ostream&, const Position&);
 std::ostream& operator<<(std::ostream&, const PositionInFlatTree&);