Remove bindings-dart

sky/engine/bindings-dart/core/dart/dart-native-extensions.gyp

-{
-  'variables': {
-    'dart_dir': '../../../../../../dart',
-  },
-
-  'targets': [
-    {
-      'target_name': 'dart_library',
-      'type': 'shared_library',
-      'dependencies': [
-        '<(dart_dir)/runtime/dart-runtime.gyp:libdart',
-      ],
-      'sources': [
-        'shared_lib/DartLibraryMain.cpp',
-      ],
-      'conditions': [
-        ['OS=="linux"', {
-          'cflags': [
-            '-fPIC',
-          ],
-          'ldflags!': [
-            # Remove to allow Dart_ APIs to be exported.
-            '-Wl,--exclude-libs=ALL',
-          ],
-        }],
-        ['OS=="android"', {
-          'cflags': [
-            '-fPIC',
-          ],
-          'link_settings': {
-            'libraries': [
-              '-landroid',
-              '-llog',
-            ],
-          },
-          'ldflags!': [
-            # Remove to allow Dart_ APIs to be exported.
-            '-Wl,--exclude-libs=ALL',
-          ],
-          'ldflags': [
-            '-rdynamic',
-          ],
-          'all_dependent_settings': {
-            'ldflags!': [
-              # See https://code.google.com/p/chromium/issues/detail?id=266155
-              # When compiling dependent shared libraries, Android's GCC linker
-              # reports a warning that this library is referencing isspace from
-              # libjingle.
-              # isspace should be inlined and is not reported as unresolved in
-              # this library.
-              '-Wl,--fatal-warnings',
-            ],
-          },
-        }],
-      ],
-    },
-  ],
-}