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

build/win/asan.gyp

+# Copyright (c) 2014 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.
+
+{
+   'targets': [
+     {
+       'target_name': 'asan_dynamic_runtime',
+       'type': 'none',
+       'variables': {
+         # Every target is going to depend on asan_dynamic_runtime, so allow
+         # this one to depend on itself.
+         'prune_self_dependency': 1,
+       },
+       'conditions': [
+         ['OS=="win"', {
+           'copies': [
+             {
+               'destination': '<(PRODUCT_DIR)',
+               'files': [
+                 # Path is relative to this GYP file.
+                 '<(DEPTH)/<(make_clang_dir)/lib/clang/<!(python <(DEPTH)/tools/clang/scripts/update.py --print-clang-version)/lib/windows/clang_rt.asan_dynamic-i386.dll',
+               ],
+             },
+           ],
+         }],
+       ],
+     },
+   ],
+}