Regularize some naming to make BUILD.gn files easier to write.

runtime/lib/corelib_sources.gypi

Index: runtime/lib/corelib_sources.gypi
===================================================================
--- runtime/lib/corelib_sources.gypi	(revision 41495)
+++ runtime/lib/corelib_sources.gypi	(working copy)
@@ -1,62 +0,0 @@
-# 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.
-
-# Sources visible via default library.
-
-{
-  'sources': [
-    'core_patch.dart',
-    # The above file needs to be first as it imports required libraries.
-    'array.cc',
-    'array.dart',
-    'array_patch.dart',
-    'bigint.dart',
-    'bool.cc',
-    'bool_patch.dart',
-    'date.cc',
-    'date_patch.dart',
-    'double.cc',
-    'double.dart',
-    'double_patch.dart',
-    'errors.cc',
-    'errors_patch.dart',
-    'expando_patch.dart',
-    'function.cc',
-    'function.dart',
-    'function_patch.dart',
-    'growable_array.cc',
-    'growable_array.dart',
-    'identical.cc',
-    'identical_patch.dart',
-    'immutable_map.dart',
-    'integers.cc',
-    'integers.dart',
-    'integers_patch.dart',
-    'invocation_mirror.h',
-    'invocation_mirror_patch.dart',
-    'lib_prefix.dart',
-    'map_patch.dart',
-    'null_patch.dart',
-    'num.cc',
-    'num.dart',
-    'object.cc',
-    'object_patch.dart',
-    'regexp.cc',
-    'regexp_jsc.cc',
-    'regexp_jsc.h',
-    'regexp_patch.dart',
-    'stacktrace.cc',
-    'stacktrace_patch.dart',
-    'stopwatch.cc',
-    'stopwatch_patch.dart',
-    'string.cc',
-    'string_buffer_patch.dart',
-    'string_patch.dart',
-    'type_patch.dart',
-    'uri.cc',
-    'uri_patch.dart',
-    'weak_property.cc',
-    'weak_property.dart',
-  ],
-}