Remove the core library stubbing infrastructure.

utils/pub/pub.gyp

Index: utils/pub/pub.gyp
diff --git a/utils/pub/pub.gyp b/utils/pub/pub.gyp
index 13d0b09e31556032eda28a3075a8add368d0650b..f15df3299a513a1ba895aa05019cc25ddebffa9c 100644
--- a/utils/pub/pub.gyp
+++ b/utils/pub/pub.gyp
@@ -37,34 +37,6 @@
         },
       ],
     },
-    {
-      'target_name': 'core_stubs',
-      'type': 'none',
-      'dependencies': [
-        '../../runtime/dart-runtime.gyp:dart',
-        '../../pkg/pkg.gyp:pkg_packages',
-        '../../pkg/pkg_files.gyp:pkg_files_stamp'
-      ],
-      'actions': [
-        {
-          'action_name': 'generate_core_stubs',
-          'inputs': [
-            '<(PRODUCT_DIR)/<(EXECUTABLE_PREFIX)dart<(EXECUTABLE_SUFFIX)',
-            '../../sdk/lib/_internal/libraries.dart',
-            '<(SHARED_INTERMEDIATE_DIR)/pkg_files.stamp',
-          ],
-          'outputs': [
-            '<(SHARED_INTERMEDIATE_DIR)/core_stubs/dart_io.dart',
-          ],
-          'action': [
-            '<(PRODUCT_DIR)/<(EXECUTABLE_PREFIX)dart<(EXECUTABLE_SUFFIX)',
-            '--package-root=<(PRODUCT_DIR)/packages/',
-            '../../pkg/stub_core_library/bin/stub_core_library.dart',
-            '<(SHARED_INTERMEDIATE_DIR)/core_stubs',
-          ],
-        }
-      ]
-    },
     # Other targets depend on pub files, but have to many inputs, which causes
     # issues on some platforms.
     # This target lists all the files in sdk/lib/_internal/pub,