Add flag to disable hashing

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 73 matching lines @@
           options.dumpSrcDir, entryNode.uri, rules, options));
     }
     if (outputDir != null) {
       generators.add(options.outputDart
           ? new DartGenerator(outputDir, entryNode.uri, rules, options)
           : new JSGenerator(outputDir, entryNode.uri, rules, options));
     }
     return new Compiler._(options, resolver, reporter, rules, checker, graph,
         entryNode, generators,
         // TODO(sigmund): refactor to support hashing of the dart output?
-        options.serverMode && generators.length == 1 && !options.outputDart);
+        options.enableHashing && generators.length == 1 && !options.outputDart);
   }
 
   Compiler._(this._options, this._resolver, this._reporter, this._rules,
       this._checker, this._graph, this._entryNode, this._generators,
       this._hashing);
 
   bool _buildSource(SourceNode node) {
     if (node is HtmlSourceNode) {
       _buildHtmlFile(node);
     } else if (node is DartSourceNode) {
@@ skipping 201 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'] = segments[1];
     }
     return response.change(headers: headers);
   };
 }
 
 final _log = new Logger('dev_compiler');
 final _earlyErrorResult = new CheckerResults(const [], null, true);