Add a snapshot of flutter/engine/src/build to our sdk

build/win_precompile.gypi

+# Copyright (c) 2011 The Chromium Authors. All rights reserved.
+# Use of this source code is governed by a BSD-style license that can be
+# found in the LICENSE file.
+
+# Include this file to make targets in your .gyp use the default
+# precompiled header on Windows, in debug builds only as the official
+# builders blow up (out of memory) if precompiled headers are used for
+# release builds.
+
+{
+  'conditions': [
+    ['OS=="win" and chromium_win_pch==1', {
+        'target_defaults': {
+          'msvs_precompiled_header': '<(DEPTH)/build/precompile.h',
+          'msvs_precompiled_source': '<(DEPTH)/build/precompile.cc',
+          'sources': ['<(DEPTH)/build/precompile.cc'],
+        }
+      }],
+  ],
+}