Add support for loading scripts from http

runtime/bin/bin.gypi

 # Copyright (c) 2012, 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.
 
 {
   'variables': {
     # We place most generated source files in LIB_DIR (rather than, say
     # SHARED_INTERMEDIATE_DIR) because it is toolset specific. This avoids
     # two problems. First, if a generated source file has architecture specific
     # code, we'll get two different files in two different directories. Second,
@@ skipping 233 matching lines @@
       ],
     },
     {
       # Completely statically linked binary for generating snapshots.
       'target_name': 'gen_snapshot',
       'type': 'executable',
       'toolsets':['host'],
       'dependencies': [
         'libdart_withcore',
         'libdart_builtin',
+        'libdart_io',
       ],
       'include_dirs': [
         '..',
       ],
       'sources': [
         'gen_snapshot.cc',
         # Very limited native resolver provided.
         'builtin_gen_snapshot.cc',
         'builtin.cc',
         'builtin.h',
@@ skipping 417 matching lines @@
                 '-fPIC',
               ],
             }],
           ],
         },
       ],
     }],
   ],
 }