Internal libraries supported.

sdk/lib/_internal/compiler/implementation/source_file_provider.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 source_file_provider;
 
 import 'dart:async';
 import 'dart:uri';
 import 'dart:io';
 import 'dart:utf';
@@ skipping 15 matching lines @@
 }
 
 class SourceFileProvider {
   bool isWindows = (Platform.operatingSystem == 'windows');
   Uri cwd = getCurrentDirectory();
   Map<String, SourceFile> sourceFiles = <String, SourceFile>{};
   int dartBytesRead = 0;
 
   Future<String> readStringFromUri(Uri resourceUri) {
     if (resourceUri.scheme != 'file') {
-      throw new ArgumentError(resourceUri);
+      throw new ArgumentError("Unknown scheme in uri '$resourceUri'");
     }
     String source;
     try {
       source = readAll(uriPathToNative(resourceUri.path));
     } on FileIOException catch (ex) {
       throw 'Error: Cannot read "${relativize(cwd, resourceUri, isWindows)}" '
             '(${ex.osError}).';
     }
     dartBytesRead += source.length;
     sourceFiles[resourceUri.toString()] =
@@ skipping 65 matching lines @@
       print(file.getLocationMessage(color(message), begin, end, true, color));
     }
     if (fatal && throwOnError) {
       isAborting = true;
       throw new AbortLeg(message);
     }
   }
 }