[infra] Translate _sources.gypi files to _sources.gni files

runtime/platform/platform_headers.gypi

Index: runtime/platform/platform_headers.gypi
diff --git a/runtime/platform/platform_headers.gypi b/runtime/platform/platform_headers.gypi
deleted file mode 100644
index 2d4733798520fe726e962471f4ed593d7da85a60..0000000000000000000000000000000000000000
--- a/runtime/platform/platform_headers.gypi
+++ /dev/null
@@ -1,22 +0,0 @@
-# Copyright (c) 2012, 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.
-
-# This file contains headers shared between the vm and bin components.
-{
-  'sources': [
-    'address_sanitizer.h',
-    'allocation.h',
-    'assert.h',
-    'c99_support_win.h',
-    'floating_point.h',
-    'floating_point_win.h',
-    'globals.h',
-    'growable_array.h',
-    'hashmap.h',
-    'inttypes_support_win.h',
-    'memory_sanitizer.h',
-    'text_buffer.h',
-    'utils.h',
-  ],
-}