Make pub strong-mode clean.

lib/src/command/build.dart

 // Copyright (c) 2013, 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 'package:barback/barback.dart';
 import 'package:path/path.dart' as path;
 
 import '../barback/asset_environment.dart';
@@ skipping 35 matching lines @@
         help: "Directory to write build outputs to.",
         defaultsTo: "build");
   }
 
   Future onRunTransformerCommand() async {
     cleanDir(outputDirectory);
 
     var errorsJson = [];
     var logJson = [];
 
-    var environmentConstants = new Map.fromIterable(argResults["define"],
+    var environmentConstants = new Map<String, String>.fromIterable(
+        argResults["define"],
         key: (pair) => pair.split("=").first,
         value: (pair) => pair.split("=").last);
 
-    // Since this server will only be hit by the transformer loader and isn't
-    // user-facing, just use an IPv4 address to avoid a weird bug on the
-    // OS X buildbots.
-    return AssetEnvironment.create(entrypoint, mode,
+    try {
+      // Since this server will only be hit by the transformer loader and isn't
+      // user-facing, just use an IPv4 address to avoid a weird bug on the OS X
+      // buildbots.
+      var environment = await AssetEnvironment.create(entrypoint, mode,
             environmentConstants: environmentConstants,
-            useDart2JS: true)
-        .then((environment) {
+            useDart2JS: true);
+
       // Show in-progress errors, but not results. Those get handled
       // implicitly by getAllAssets().
       environment.barback.errors.listen((error) {
         log.error(log.red("Build error:\n$error"));
 
         if (log.json.enabled) {
           // Wrap the error in a map in case we end up decorating it with
           // more properties later.
           errorsJson.add({
             "error": error.toString()
           });
         }
       });
 
       // If we're using JSON output, the regular server logging is disabled.
       // Instead, we collect it here to include in the final JSON result.
       if (log.json.enabled) {
         environment.barback.log.listen(
             (entry) => logJson.add(_logEntryToJson(entry)));
       }
 
-      return log.progress("Building ${entrypoint.root.name}", () {
+      var assets = await log.progress("Building ${entrypoint.root.name}",
+          () async {
         // Register all of the build directories.
         // TODO(rnystrom): We don't actually need to bind servers for these, we
         // just need to add them to barback's sources. Add support to
         // BuildEnvironment for going the latter without the former.
-        return Future.wait(sourceDirectories.map(
-            (dir) => environment.serveDirectory(dir))).then((_) {
+        await Future.wait(sourceDirectories.map(
+            (dir) => environment.serveDirectory(dir)));
 
-          return environment.barback.getAllAssets();
-        });
-      }).then((assets) {
-        // Find all of the JS entrypoints we built.
-        var dart2JSEntrypoints = assets
-            .where((asset) => asset.id.path.endsWith(".dart.js"))
-            .map((asset) => asset.id);
+        return environment.barback.getAllAssets();
+      });
 
-        return Future.wait(assets.map(_writeAsset)).then((_) {
-          return _copyBrowserJsFiles(dart2JSEntrypoints, assets);
-        }).then((_) {
-          log.message('Built $builtFiles ${pluralize('file', builtFiles)} '
-              'to "$outputDirectory".');
+      // Find all of the JS entrypoints we built.
+      var dart2JSEntrypoints = assets
+          .where((asset) => asset.id.path.endsWith(".dart.js"))
+          .map((asset) => asset.id);
 
-          log.json.message({
-            "buildResult": "success",
-            "outputDirectory": outputDirectory,
-            "numFiles": builtFiles,
-            "log": logJson
-          });
-        });
+      await Future.wait(assets.map(_writeAsset));
+      await _copyBrowserJsFiles(dart2JSEntrypoints, assets);
+
+      log.message('Built $builtFiles ${pluralize('file', builtFiles)} '
+          'to "$outputDirectory".');
+
+      log.json.message({
+        "buildResult": "success",
+        "outputDirectory": outputDirectory,
+        "numFiles": builtFiles,
+        "log": logJson
       });
-    }).catchError((error) {
+    } on BarbackException catch (_) {
       // If [getAllAssets()] throws a BarbackException, the error has already
       // been reported.
-      if (error is! BarbackException) throw error;
-
       log.error(log.red("Build failed."));
       log.json.message({
         "buildResult": "failure",
         "errors": errorsJson,
         "log": logJson
       });
 
       return flushThenExit(exit_codes.DATA);
-    });
+    }
   }
 
   /// Writes [asset] to the appropriate build directory.
   ///
   /// If [asset] is in the special "packages" directory, writes it to every
   /// build directory.
   Future _writeAsset(Asset asset) async {
     // In release mode, strip out .dart files since all relevant ones have been
     // compiled to JavaScript already.
     if (mode == BarbackMode.RELEASE && asset.id.extension == ".dart") {
@@ skipping 116 matching lines @@
         "end": {
           "line": entry.span.end.line,
           "column": entry.span.end.column
         },
       };
     }
 
     return data;
   }
 }