Add a snapshot for docgen and use it in the build

pkg/docgen/bin/dartdoc.py

 #!/usr/bin/env python
 #
 # Copyright (c) 2013, 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.
 
 # Run this script to generate documentation for a directory and serve
 # the results to localhost for viewing in the browser.
 
 import optparse
@@ skipping 69 matching lines @@
 
 def GenerateAllDocs(docgen_options):
   '''Generate all documentation for the SDK and all packages in the repository.
   We first attempt to run the quickest path to generate all docs, but if that
   fails, we fall back on a slower option.'''
 # TODO(alanknight): The --append option doesn't work properly. It overwrites
 # existing files with new information. Known symptom is that it loses subclasses
 # from the SDK and includes only the ones from pkg. So right now our only option
 # is to do everything in one pass.
   doc_dir = join(DART_DIR, 'pkg')
-  cmd_lst = [DART_EXECUTABLE, '--old_gen_heap_size=1024',
+  cmd_lst = [DART_EXECUTABLE, 
       '--package-root=%s' % PACKAGE_ROOT, 'docgen.dart', '--include-sdk' ]
   cmd_str = ' '.join(AddUserDocgenOptions(cmd_lst, docgen_options, True))
   # Try to run all pkg docs together at once as it's fastest.
   (return_code, _) = ExecuteCommandString('%s %s' % (cmd_str, doc_dir))
   if return_code != 0:
     # We failed to run all the pkg docs, so try to generate docs for each pkg
     # individually.
     failed_pkgs = []
     for directory in os.listdir(join(DART_DIR, 'pkg')):
       doc_dir = join(DART_DIR, 'pkg', directory)
@@ skipping 55 matching lines @@
       print (
         "\nPoint your browser to the address of the 'default' server below.")
       raw_input("Press <RETURN> to terminate the server.\n\n")
       server.terminate()
     finally:
       os.chdir(cwd)
       subprocess.call(['rm', '-rf', 'dartdoc-viewer'])
 
 if __name__ == '__main__':
   main()