Move writeOutline() and writeProgram() out of KernelTarget.

pkg/front_end/lib/src/fasta/compile_platform.dart

 // Copyright (c) 2016, 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.
 
 library fasta.compile_platform;
 
 import 'dart:async' show Future;
 
 import 'package:front_end/src/fasta/kernel/utils.dart';
 import 'ticker.dart' show Ticker;
@@ skipping 58 matching lines @@
   TranslateUri uriTranslator =
       await TranslateUri.parse(c.fileSystem, patchedSdk, c.options.packages);
   ticker.logMs("Read packages file");
 
   DillTarget dillTarget = new DillTarget(ticker, uriTranslator);
   KernelTarget kernelTarget = new KernelTarget(c.fileSystem, dillTarget,
       uriTranslator, c.options.strongMode, c.uriToSource);
 
   kernelTarget.read(Uri.parse("dart:core"));
   await dillTarget.buildOutlines();
-  await kernelTarget.buildOutlines();
-  await kernelTarget.writeOutline(outlineOutput);
+  var outline = await kernelTarget.buildOutlines();
+  await writeProgramToFileUri(ticker, outlineOutput, outline,
+      isFullProgram: false);
 
   if (exitCode != 0) return null;
+
   var program = await kernelTarget.buildProgram(verify: c.options.verify);
   if (c.options.dumpIr) printProgramText(program);
-  await kernelTarget.writeProgram(fullOutput);
+  await writeProgramToFileUri(ticker, fullOutput, program, isFullProgram: true);
   await kernelTarget.writeDepsFile(fullOutput, deps);
 }