Copy resources refered to in the HTML to the output folder

lib/src/utils.dart

 // Copyright (c) 2015, 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.
 
 /// Holds a couple utility functions used at various places in the system.
 library dev_compiler.src.utils;
 
 import 'dart:io';
 
 import 'package:path/path.dart' as path;
@@ skipping 280 matching lines @@
   return new SourceSpan(locationForOffset(unit, uri, begin),
       locationForOffset(unit, uri, end), '$text');
 }
 
 /// Computes a hash for the given contents.
 String computeHash(String contents) {
   if (contents == null || contents == '') return null;
   return CryptoUtils.bytesToHex((new MD5()..add(contents.codeUnits)).close());
 }
 
-String resourceOutputPath(Uri resourceUri) {
+/// Computes a hash for the given file path (reads the contents in binary form).
+String computeHashFromFile(String filepath) {
+  var bytes = new File(filepath).readAsBytesSync();
+  return CryptoUtils.bytesToHex((new MD5()..add(bytes)).close());
+}
+
+String resourceOutputPath(Uri resourceUri, Uri entryUri) {
   if (resourceUri.scheme == 'package') return resourceUri.path;
 
-  // Only support file:/// urls for resources in the dev_compiler package
   if (resourceUri.scheme != 'file') return null;
+  var filepath = resourceUri.path;
+  var relativePath = path.relative(filepath, from: path.dirname(entryUri.path));
+
+  // File:/// urls can be for resources in the same project or resources from
+  // the dev_compiler package. For now we only support relative paths going
+  // further inside the folder where the entrypoint is located, otherwise we
+  // assume this is a runtime resource from the dev_compiler.
+  if (!relativePath.startsWith('..')) return relativePath;
   var segments = resourceUri.pathSegments;
   var len = segments.length;
   if (segments.length < 4 ||
       segments[len - 2] != 'runtime' ||
       segments[len - 3] != 'lib' ||
       // If loaded from sources this will be exactly dev_compiler, otherwise it
       // can be the name in the pub cache (typically dev_compiler-version).
       !segments[len - 4].startsWith('dev_compiler')) {
     return null;
   }
   return path.joinAll(['dev_compiler']..addAll(segments.skip(len - 2)));
 }