Overhaul tree IR visitor and rename IR classes.

pkg/compiler/lib/src/use_unused_api.dart

 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 /// This file use methods that aren't used by dart2js.dart, but that we wish to
 /// keep anyway. This might be general API that isn't currently in use,
 /// debugging aids, or API only used for testing (see TODO below).
 
 library dart2js.use_unused_api;
 
 import '../compiler.dart' as api;
 
 import 'colors.dart' as colors;
 import 'constants/values.dart' as constants;
 import 'cps_ir/cps_ir_builder.dart' as ir_builder;
 import 'cps_ir/cps_ir_builder_task.dart' as ir_builder;
 import 'cps_ir/cps_ir_nodes_sexpr.dart' as cps_ir_nodes_sexpr;
+import 'tree_ir/tree_ir_nodes.dart' as tree_ir;
 import 'dart_types.dart' as dart_types;
 import 'dart2js.dart' as dart2js;
 import 'dart2jslib.dart' as dart2jslib;
 import 'elements/elements.dart' as elements;
 import 'elements/modelx.dart' as modelx;
 import 'elements/visitor.dart' as elements_visitor;
 import 'filenames.dart' as filenames;
 import 'inferrer/concrete_types_inferrer.dart' as concrete_types_inferrer;
 import 'inferrer/type_graph_inferrer.dart' as type_graph_inferrer;
 import 'io/code_output.dart' as io;
@@ skipping 38 matching lines @@
   useCodeBuffer(null);
   usedByTests();
   useElements(null, null, null, null, null);
   useIr(null, null);
   useCompiler(null);
   useTypes();
   useCodeEmitterTask(null);
   useScript(null);
   useProgramBuilder(null);
   useSemanticVisitor();
+  useTreeVisitors();
 }
 
 useApi() {
   api.ReadStringFromUri uri;
 }
 
 void useConstant(constants.ConstantValue constant,
                  dart2jslib.ConstantSystem cs) {
   constant.isObject;
   cs.isBool(constant);
@@ skipping 194 matching lines @@
 
 useProgramBuilder(program_builder.ProgramBuilder builder) {
   builder.buildMethodHackForIncrementalCompilation(null);
   builder.buildFieldsHackForIncrementalCompilation(null);
 }
 
 useSemanticVisitor() {
   new semantic_visitor.BulkVisitor().apply(null, null);
   new semantic_visitor.TraversalVisitor(null).apply(null, null);
 }
+
+class DummyTreeVisitor extends tree_ir.RootVisitor
+                          with tree_ir.InitializerVisitor {
+  visitFunctionDefinition(tree_ir.FunctionDefinition node) {}
+  visitConstructorDefinition(tree_ir.ConstructorDefinition node) {}
+  visitFieldDefinition(tree_ir.FieldDefinition node) {}
+
+  visitFieldInitializer(tree_ir.FieldInitializer node) {}
+  visitSuperInitializer(tree_ir.SuperInitializer node) {}
+}
+
+useTreeVisitors() {
+  new DummyTreeVisitor().visitRootNode(null);
+  new DummyTreeVisitor().visitInitializer(null);
+}