Rename apiimpl.Compiler to CompilerImpl.

tests/compiler/dart2js/sourcemaps/sourcemap_helper.dart

 // Copyright (c) 2015, 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 sourcemap.helper;
 
 import 'dart:async';
 import 'package:compiler/compiler_new.dart';
 import 'package:compiler/src/apiimpl.dart' as api;
 import 'package:compiler/src/null_compiler_output.dart' show NullSink;
@@ skipping 102 matching lines @@
   Future<List<SourceMapInfo>> process(
       List<String> options,
       {bool verbose: true}) async {
     OutputProvider outputProvider = outputToFile
         ? new OutputProvider()
         : new CloningOutputProvider(targetUri, sourceMapFileUri);
     if (options.contains('--use-new-source-info')) {
       if (verbose) print('Using the new source information system.');
       useNewSourceInfo = true;
     }
-    api.Compiler compiler = await compilerFor(
+    api.CompilerImpl compiler = await compilerFor(
         outputProvider: outputProvider,
         // TODO(johnniwinther): Use [verbose] to avoid showing diagnostics.
         options: ['--out=$targetUri', '--source-map=$sourceMapFileUri']
             ..addAll(options));
     if (options.contains('--disable-inlining')) {
       if (verbose) print('Inlining disabled');
       compiler.disableInlining = true;
     }
 
     JavaScriptBackend backend = compiler.backend;
@@ skipping 195 matching lines @@
       this.jsCode,
       this.sourceLocation,
       this.dartCode,
       {this.isMissing: false});
 
   String toString() {
     return 'CodePoint[kind=$kind,js=$jsCode,dart=$dartCode,'
                      'location=$sourceLocation]';
   }
 }