Fixes for exit problems.

pkg/analyzer/lib/src/services/runtime/coverage/coverage_impl.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.
 
 /// A library for code coverage support for Dart.
 library runtime.coverage.impl;
 
 import 'dart:async';
 import 'dart:collection' show SplayTreeMap;
 import 'dart:io';
@@ skipping 101 matching lines @@
   }
 
   String getFilePath(Uri uri) {
     var path = uri.path;
     path = pathos.joinAll(uri.pathSegments);
     path = pathos.join(basePath, path);
     return pathos.normalize(path);
   }
 
   Future sendFile(HttpRequest request, File file) {
-    file.resolveSymbolicLinks().then((fullPath) {
+    return file.resolveSymbolicLinks().then((fullPath) {
       return file.openRead().pipe(request.response);
     });
   }
 
   bool shouldRewriteFile(String path);
 
   /// Subclasses implement this method to rewrite the provided [code] of the
   /// file with [path]. Returns some content or `null` if file content
   /// should be requested.
   String rewritePathContent(String path);
@@ skipping 197 matching lines @@
     var lastOffset = 0;
     offsetFragmentMap.forEach((offset, fragment) {
       sb.write(_code.substring(lastOffset, offset));
       sb.write(fragment);
       lastOffset = offset;
     });
     sb.write(_code.substring(lastOffset, _code.length));
     return sb.toString();
   }
 }