Delete dart_backend from compiler.

tests/compiler/dart2js/analyze_unused_dart2js_test.dart

Index: tests/compiler/dart2js/analyze_unused_dart2js_test.dart
diff --git a/tests/compiler/dart2js/analyze_unused_dart2js_test.dart b/tests/compiler/dart2js/analyze_unused_dart2js_test.dart
index 8106a06e92c5c49c41e8f2f8937b1b56e4211b73..a17914eda74e3a9ab106cc0ca904cd8e48943b5f 100644
--- a/tests/compiler/dart2js/analyze_unused_dart2js_test.dart
+++ b/tests/compiler/dart2js/analyze_unused_dart2js_test.dart
@@ -23,9 +23,6 @@ const Map<String, List<String>> WHITE_LIST = const {
       "The method 'asAssert' is never called.",
       "The method 'asLiteralBool' is never called."],
 
-  // Some things in dart_printer are not yet used
-  "lib/src/dart_backend/backend_ast_nodes.dart": const [" is never "],
-
   // Uncalled methods in SemanticSendVisitor and subclasses.
   "lib/src/resolution/semantic_visitor.dart": const [
       "The method 'error"],
@@ -56,10 +53,6 @@ const Map<String, List<String>> WHITE_LIST = const {
     "accept", "CreateFunction",
   ],
 
-  "lib/src/dart_backend/backend_ast_to_frontend_ast.dart": const [
-    " is never "
-  ],
-
   // Useful utility functions that are not currently used.
   "lib/src/cps_ir/cps_fragment.dart": const [
     "The method 'beginLoop' is never called.",