Build Observatory as part of runtime

runtime/dart-runtime.gyp

 # Copyright (c) 2011, 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.
 
 {
   'includes': [
     'tools/gyp/runtime-configurations.gypi',
     'vm/vm.gypi',
+    'observatory/observatory.gypi',
     'bin/bin.gypi',
     'third_party/double-conversion/src/double-conversion.gypi',
     'third_party/jscre/jscre.gypi',
   ],
   'variables': {
     'gen_source_dir': '<(SHARED_INTERMEDIATE_DIR)',
     'version_in_cc_file': 'vm/version_in.cc',
     'version_cc_file': '<(gen_source_dir)/version.cc',
 
     'libdart_deps': ['libdart_lib_withcore', 'libdart_lib', 'libdart_vm',
@@ skipping 136 matching lines @@
         }],
         ['OS=="linux"', {
           'cflags': [
             '-fPIC',
           ],
         }],
       ],
     },
   ],
 }