Cleanup support DDC debugging tools.

lib/src/dartdevc/dartdevc_environment.dart

 // Copyright (c) 2017, 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.
 
 import 'dart:async';
 import 'dart:convert';
 import 'dart:io';
 
 import 'package:async/async.dart';
 import 'package:barback/barback.dart';
@@ skipping 191 matching lines @@
         asset.id.extension == '.dart' &&
         topLevelDir(asset.id.path) == moduleDir);
     if (moduleAssets.isEmpty) throw new AssetNotFoundException(id);
     var moduleMode =
         moduleDir == 'lib' ? ModuleMode.public : ModuleMode.private;
     var modules = await computeModules(moduleMode, moduleAssets);
     var encoded = JSON.encode(modules);
     return new Asset.fromString(id, encoded);
   }
 
+  /// Whether [_sdkResources] has an asset matching [id].
   bool _hasJsResource(AssetId id) =>
       _sdkResources.containsKey(p.url.basename(id.path));
 
   /// Builds [_sdkResources] assets by copying them from the SDK.
   Future<Asset> _buildJsResource(AssetId id) async {
     var sdk = cli_util.getSdkDir();
     var basename = p.url.basename(id.path);
     var resourcePath = _sdkResources[basename];
     if (resourcePath == null) return null;
     return new Asset.fromPath(id, p.url.join(sdk.path, resourcePath));
@@ skipping 86 matching lines @@
 
   /// Reads a [Result] from the actual underlying caches, or returns `null`.
   Future<Result> _getResult(AssetId id) {
     var packageCache = _assets[id.package];
     if (packageCache == null) return null;
     var futureResult = packageCache[id.path];
     if (futureResult == null) return null;
     return futureResult;
   }
 }