HTTP loading tests and package root support

runtime/bin/builtin.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.
 
 library builtin;
 import 'dart:io';
 
 int _httpRequestResponseCode = 0;
 String _httpRequestStatusString;
 var _httpRequestResponse;
@@ skipping 55 matching lines @@
   }
 }
 
 _setPackageRoot(String packageRoot) {
   // TODO(mattsh) - refactor windows drive and path handling code
   // so it can be used here if needed.
   _packageRoot = packageRoot;
 }
 
 String _resolveScriptUri(String cwd, String scriptName, bool isWindows) {
+  var scriptUri = Uri.parse(scriptName);
+  if (scriptUri.scheme == 'http') {
+    _entrypoint = scriptUri;
+    _logResolution("# Resolved script to: $_entrypoint");
+    return _entrypoint.toString();
+  }
   _logResolution("# Current working directory: $cwd");
   _logResolution("# ScriptName: $scriptName");
   if (isWindows) {
     // For Windows we need to massage the paths a bit according to
     // http://blogs.msdn.com/b/ie/archive/2006/12/06/file-uris-in-windows.aspx
     //
     // Convert
     // C:\one\two\three
     // to
     // /C:/one/two/three
@@ skipping 103 matching lines @@
     var wrong = 'package://$path';
 
     throw "URIs using the 'package:' scheme should look like "
           "'$right', not '$wrong'.";
   }
 
   var path;
   if (_packageRoot != null) {
     path = "${_packageRoot}${uri.path}";
   } else {
-    path = _entrypoint.resolve('packages/${uri.path}').path;
+    if (_entrypoint.scheme == 'http') {
+      path = _entrypoint.resolve('packages/${uri.path}').toString();
+    } else {
+      path = _entrypoint.resolve('packages/${uri.path}').path;
+    }
   }
 
   _logResolution("# Package: $path");
   return path;
 }
 
 String _filePathFromHttpUri(Uri uri) {
   _logResolution('# Path: $uri');
   return uri.toString();
 }