simplify computing of runtime file locations

lib/devc.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.
 
 /// Command line tool to run the checker on a Dart program.
 library dev_compiler.devc;
 
 import 'dart:async';
 import 'dart:convert';
 import 'dart:io';
@@ skipping 121 matching lines @@
     var filename = path.basename(node.uri.path);
     String outputFile = path.join(outputDir, filename);
     new File(outputFile).writeAsStringSync(output);
   }
 
   void _buildResourceFile(ResourceSourceNode node) {
     // ResourceSourceNodes files that just need to be copied over to the output
     // location. These can be external dependencies or pieces of the
     // dev_compiler runtime.
     if (outputDir == null) return;
-    var filepath = resourceOutputPath(node.uri, _entryNode.uri);
+    var filepath =
+        resourceOutputPath(node.uri, _entryNode.uri, options.runtimeDir);
     assert(filepath != null);
     filepath = path.join(outputDir, filepath);
     var dir = path.dirname(filepath);
     new Directory(dir).createSync(recursive: true);
     new File.fromUri(node.source.uri).copySync(filepath);
     if (_hashing) node.cachingHash = computeHashFromFile(filepath);
   }
 
   bool _isEntry(DartSourceNode node) {
     if (_entryNode is DartSourceNode) return _entryNode == node;
@@ skipping 176 matching lines @@
       // Note: the cache-control header should be enough, but this doesn't hurt
       // and can help renew the policy after it expires.
       headers['ETag'] = hash;
     }
     return response.change(headers: headers);
   };
 }
 
 final _log = new Logger('dev_compiler');
 final _earlyErrorResult = new CheckerResults(const [], null, true);