Rip out dart:io from pkg/http wherever possible.

sdk/lib/_internal/pub/lib/src/utils.dart

 // Copyright (c) 2012, 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.
 
 /// Generic utility functions. Stuff that should possibly be in core.
 library pub.utils;
 
 import 'dart:async';
 import "dart:collection";
 import "dart:convert";
 import 'dart:io';
 import 'dart:isolate';
 @MirrorsUsed(targets: 'pub.io')
 import 'dart:mirrors';
 
 import "package:analyzer/analyzer.dart";
 import "package:crypto/crypto.dart";
+import "package:http/http.dart" as http;
 import 'package:path/path.dart' as path;
 import "package:stack_trace/stack_trace.dart";
 
 import '../../asset/dart/serialize.dart';
 
 export '../../asset/dart/utils.dart';
 
 /// A pair of values.
 class Pair<E, F> {
   E first;
@@ skipping 798 matching lines @@
 }
 
 /// Throw a [ApplicationException] with [message].
 void fail(String message, [innerError, StackTrace innerTrace]) {
   throw new ApplicationException(message, innerError, innerTrace);
 }
 
 /// All the names of user-facing exceptions.
 final _userFacingExceptions = new Set<String>.from([
   'ApplicationException',
+  // This refers to http.ClientException.
+  'ClientException',
   // Errors coming from the Dart analyzer are probably caused by syntax errors
   // in user code, so they're user-facing.
   'AnalyzerError', 'AnalyzerErrorGroup',
   // An error spawning an isolate probably indicates a transformer with an
   // invalid import.
   'IsolateSpawnException',
   // TODO(nweiz): clean up the dart:io errors when issue 9955 is fixed.
-  'FileSystemException', 'HttpException', 'HttpException', 'OSError',
+  'FileSystemException', 'HttpException', 'OSError',
   'ProcessException', 'SocketException', 'WebSocketException'
 ]);
 
 /// Returns whether [error] is a user-facing error object. This includes both
 /// [ApplicationException] and any dart:io errors.
 bool isUserFacingException(error) {
   if (error is CrossIsolateException) {
     return _userFacingExceptions.contains(error.type);
   }
 
   // TODO(nweiz): unify this list with _userFacingExceptions when issue 5897 is
   // fixed.
   return error is ApplicationException ||
     error is AnalyzerError ||
     error is AnalyzerErrorGroup ||
     error is IsolateSpawnException ||
     error is FileSystemException ||
     error is HttpException ||
-    error is HttpException ||
+    error is http.ClientException ||
     error is OSError ||
     error is ProcessException ||
     error is SocketException ||
     error is WebSocketException;
 }