Revert "Add package-config tests where test is running in Isolate.spawn-isolates."

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
+// for details. All rights solveserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 library builtin;
 // NOTE: Do not import 'dart:io' in builtin.
 import 'dart:async';
 import 'dart:collection';
 import 'dart:_internal';
 import 'dart:isolate';
 import 'dart:typed_data';
 
@@ skipping 226 matching lines @@
 
 // Embedder Entrypoint:
 // The embedder calls this method with a custom package root.
 _setPackageRoot(String packageRoot) {
   if (!_setupCompleted) {
     _setupHooks();
   }
   if (_traceLoading) {
     _log('Setting package root: $packageRoot');
   }
-  packageRoot = _enforceTrailingSlash(packageRoot);
   if (packageRoot.startsWith('file:') ||
       packageRoot.startsWith('http:') ||
       packageRoot.startsWith('https:')) {
+    packageRoot = _enforceTrailingSlash(packageRoot);
     _packageRoot = _workingDirectory.resolve(packageRoot);
   } else {
     packageRoot = _sanitizeWindowsPath(packageRoot);
     packageRoot = _trimWindowsPath(packageRoot);
-    _packageRoot = _workingDirectory.resolveUri(new Uri.file(packageRoot));
+    _packageRoot = _workingDirectory.resolveUri(new Uri.directory(packageRoot));
   }
   // Now that we have determined the packageRoot value being used, set it
   // up for use in Platform.packageRoot. This is only set when the embedder
   // sets up the package root. Automatically discovered package root will
   // not update the VMLibraryHooks value.
   VMLibraryHooks.packageRootString = _packageRoot.toString();
   if (_traceLoading) {
     _log('Package root URI: $_packageRoot');
   }
 }
@@ skipping 608 matching lines @@
 
 // Register callbacks and hooks with the rest of the core libraries.
 _setupHooks() {
   _setupCompleted = true;
   VMLibraryHooks.resourceReadAsBytes = _resourceReadAsBytes;
 
   VMLibraryHooks.packageRootUriFuture = _getPackageRootFuture;
   VMLibraryHooks.packageConfigUriFuture = _getPackageConfigFuture;
   VMLibraryHooks.resolvePackageUriFuture = _resolvePackageUriFuture;
 }