Another case of VM using Uri.resolve on something not a URI reference.

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';
 import 'dart:async';
 import 'dart:convert';
 // import 'root_library'; happens here from C Code
 
@@ skipping 179 matching lines @@
   _workingWindowsDrivePrefix = _extractDriveLetterPrefix(cwd);
   _workingDirectoryUri = new Uri.file(cwd);
   if (!_workingDirectoryUri.path.endsWith("/")) {
     var directoryPath = _workingDirectoryUri.path + "/";
     _workingDirectoryUri = _workingDirectoryUri.resolve(directoryPath);
   }
 
   _logResolution('# Working Directory: $cwd');
 }
 
+Uri _uriFromPathOrUri(String location) {
+  if (location.startsWith('file:') ||
+      location.startsWith('http:') ||
+      location.startsWith('https:')) {
+    return Uri.parse(location);
+  }
+  return new Uri.file(location);
+}
 
 _setPackageRoot(String packageRoot) {
   packageRoot = _enforceTrailingSlash(packageRoot);
-  if (packageRoot.startsWith('file:') ||
-      packageRoot.startsWith('http:') ||
-      packageRoot.startsWith('https:')) {
-    _packageRoot = _workingDirectoryUri.resolve(packageRoot);
-  } else {
-    _packageRoot = _workingDirectoryUri.resolveUri(new Uri.file(packageRoot));
-  }
+  _packageRoot =
+      _workingDirectoryUri.resolveUri(_uriFromPathOrUri(packageRoot));
   _logResolution('# Package root: $packageRoot -> $_packageRoot');
 }
 
 
 String _resolveScriptUri(String scriptName) {
   if (_workingDirectoryUri == null) {
     throw 'No current working directory set.';
   }
-  var scriptUri;
-  if (scriptName.startsWith("file:") ||
-      scriptName.startsWith("http:") ||
-      scriptName.startsWith("https:")) {
-    scriptUri = Uri.parse(scriptName);
-  } else {
-    // Assume it's a file name.
-    scriptUri = new Uri.file(scriptName);
-  }
+  var scriptUri = _uriFromPathOrUri(scriptName);
   if (scriptUri.scheme != '') {
     // Script has a scheme, assume that it is fully formed.
     _entryPointScript = scriptUri;
   } else {
     // Script does not have a scheme, assume that it is a path,
     // resolve it against the working directory.
     _entryPointScript = _workingDirectoryUri.resolve(scriptName);
   }
   _logResolution('# Resolved entry point to: $_entryPointScript');
   return _entryPointScript.toString();
@@ skipping 82 matching lines @@
   assert(_numOutstandingLoadRequests > 0);
   _numOutstandingLoadRequests--;
   _asyncLoadErrorCallback(uri, error);
 }
 
 
 // Asynchronously loads script data (source or snapshot) through
 // an http or file uri.
 _loadDataAsync(String uri) {
   uri = _resolveScriptUri(uri);
-  Uri sourceUri = Uri.parse(uri);
+  Uri sourceUri = _uriFromPathOrUri(uri);
   _numOutstandingLoadRequests++;
   _logResolution("_loadDataAsync($uri), "
                  "${_numOutstandingLoadRequests} requests outstanding");
   if (sourceUri.scheme == 'http') {
     _httpGet(sourceUri, (data) {
       _loadScript(uri, data);
     });
   } else {
     var sourceFile = new File(_filePathFromUri(uri));
     sourceFile.readAsBytes().then((data) {
@@ skipping 86 matching lines @@
   } else if (Platform.isWindows) {
     filename = '$name.dll';
   } else {
     _logResolution(
         'Native extensions not supported on ${Platform.operatingSystem}');
     throw 'Native extensions not supported on ${Platform.operatingSystem}';
   }
 
   return [path, filename, name];
 }