Remove the core library stubbing infrastructure.

create_sdk.gyp

 # Copyright (c) 2014, 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.
 
 {
   'targets': [
     {
       'target_name': 'create_sdk_internal',
       'type': 'none',
       'dependencies': [
         'runtime/dart-runtime.gyp:dart',
         'utils/compiler/compiler.gyp:dart2js',
         'utils/pub/pub.gyp:pub',
-        'utils/pub/pub.gyp:core_stubs',
         'utils/dartfmt/dartfmt.gyp:dartfmt',
         'utils/analysis_server/analysis_server.gyp:analysis_server',
         'utils/dartanalyzer/dartanalyzer.gyp:dartanalyzer',
       ],
       'actions': [
         {
           'action_name': 'create_sdk_py',
           'inputs': [
             # This is neccessary because we have all the pub test files inside
             # the pub directory instead of in tests/pub. Xcode can only handle
             # a certain amount of files in one list (also depending on the
             # length of the path from where you run). This regexp excludes
             # pub/test
             '<!@(["python", "tools/list_files.py",'
                 '"^(?!.*pub/test).*dart$",'
                 '"sdk/lib"])',
             '<!@(["python", "tools/list_files.py", "", '
                 '"sdk/lib/_internal/compiler/js_lib/preambles"])',
             '<!@(["python", "tools/list_files.py", "", "sdk/bin"])',
             'tools/create_sdk.py',
             '<(PRODUCT_DIR)/<(EXECUTABLE_PREFIX)dart<(EXECUTABLE_SUFFIX)',
             '<(SHARED_INTERMEDIATE_DIR)/dart2js.dart.snapshot',
             '<(SHARED_INTERMEDIATE_DIR)/utils_wrapper.dart.snapshot',
             '<(SHARED_INTERMEDIATE_DIR)/pub.dart.snapshot',
             '<(SHARED_INTERMEDIATE_DIR)/dartanalyzer.dart.snapshot',
             '<(SHARED_INTERMEDIATE_DIR)/dartfmt.dart.snapshot',
-            '<(SHARED_INTERMEDIATE_DIR)/core_stubs/dart_io.dart',
             '<(SHARED_INTERMEDIATE_DIR)/analysis_server.dart.snapshot',
             'tools/VERSION'
           ],
           'outputs': [
             '<(PRODUCT_DIR)/dart-sdk/README',
           ],
           'action': [
             'python',
             'tools/create_sdk.py',
             '--sdk_output_dir', '<(PRODUCT_DIR)/dart-sdk',
             '--snapshot_location', '<(SHARED_INTERMEDIATE_DIR)/'
           ],
           'message': 'Creating SDK.',
         },
       ],
     },
   ],
 }