Avoid parsing and then generating HTML for documents without Dart scripts. This is a fragile workar…

lib/src/codegen/html_codegen.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.
 
 library dev_compiler.src.codegen.html_codegen;
 
 import 'package:html/dom.dart';
 import 'package:html/parser.dart' show parseFragment;
 import 'package:logging/logging.dart' show Logger;
 import 'package:path/path.dart' as path;
@@ skipping 10 matching lines @@
 /// runtime and the compiled code, and to execute the main method of the
 /// application. When compiling to Dart, we ensure that the document contains a
 /// single Dart script tag, but otherwise emit the original document
 /// unmodified.
 String generateEntryHtml(HtmlSourceNode root, AbstractCompiler compiler) {
   var options = compiler.options;
   var document = root.document.clone(true);
   var scripts = document.querySelectorAll('script[type="application/dart"]');
   if (scripts.isEmpty) {
     _log.warning('No <script type="application/dart"> found in ${root.uri}');
-    return '${document.outerHtml}\n';
+    return root.contents;

[Jennifer Messerly, 2016/01/13 18:05:02]

This could use a comment.

   }
   scripts.skip(1).forEach((s) {
     // TODO(sigmund): allow more than one Dart script tags?
     _log.warning(s.sourceSpan.message(
         'unexpected script. Only one Dart script tag allowed '
         '(see https://github.com/dart-lang/dart-dev-compiler/issues/53).',
         color: options.useColors ? colorOf('warning') : false));
     s.remove();
   });
 
@@ skipping 77 matching lines @@
 
 /// Convert the outputPath to include the hash in it. This function is the
 /// reverse of what the server does to determine whether a request needs to have
 /// cache headers added to it.
 _addHash(String outPath, String hash) {
   // (the ____ prefix makes it look better in the web inspector)
   return '$outPath?____cached=$hash';
 }
 
 final _log = new Logger('dev_compiler.src.codegen.html_codegen');