Add CodeOutput to prepare for emission without in-memory buffers.

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_nodes_sexpr.dart' as cps_ir_nodes_sexpr;
 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;
 import 'js/js.dart' as js;
 import 'js_emitter/js_emitter.dart' as js_emitter;
 import 'source_file_provider.dart' as source_file_provider;
 import 'ssa/ssa.dart' as ssa;
 import 'tree/tree.dart' as tree;
 import 'universe/universe.dart' as universe;
 import 'util/util.dart' as util;
 
 import 'scanner/scannerlib.dart' show
     PartialClassElement,
@@ skipping 147 matching lines @@
 useFilenames() {
   filenames.appendSlash(null);
 }
 
 useSsa(ssa.HInstruction instruction) {
   instruction.isConstantNumber();
   new ssa.HAndOrBlockInformation(null, null, null);
   new ssa.HStatementSequenceInformation(null);
 }
 
-useCodeBuffer(dart2jslib.CodeBuffer buffer) {
+useCodeBuffer(io.CodeBuffer buffer) {
   buffer.writeln();
+  new io.LineColumnCodeOutput(null);
 }
 
 usedByTests() {
   // TODO(ahe): We should try to avoid including API used only for tests. In
   // most cases, such API can be moved to a test library.
   dart2jslib.World world = null;
   dart2jslib.Compiler compiler = null;
   compiler.currentlyInUserCode();
   type_graph_inferrer.TypeGraphInferrer typeGraphInferrer = null;
   source_file_provider.SourceFileProvider sourceFileProvider = null;
@@ skipping 63 matching lines @@
   new dart_types.ResolvedTypedefType(null, null, null).unalias(null);
 }
 
 useCodeEmitterTask(js_emitter.CodeEmitterTask codeEmitterTask) {
   codeEmitterTask.oldEmitter.clearCspPrecompiledNodes();
 }
 
 useScript(dart2jslib.Script script) {
   script.copyWithFile(null);
 }