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

build/ios/coverage.gypi

Index: build/ios/coverage.gypi
diff --git a/build/ios/coverage.gypi b/build/ios/coverage.gypi
new file mode 100644
index 0000000000000000000000000000000000000000..e82208902cc42428be3acfef5040037d41ea58c5
--- /dev/null
+++ b/build/ios/coverage.gypi
@@ -0,0 +1,32 @@
+# Copyright 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.
+
+{
+  'variables': {
+    'enable_coverage%': 0,
+  },
+  'conditions': [
+    ['enable_coverage', {
+        'target_defaults': {
+          'defines': [
+            'ENABLE_TEST_CODE_COVERAGE=1'
+          ],
+          'link_settings': {
+            'xcode_settings': {
+              'OTHER_LDFLAGS': [
+                '-fprofile-arcs',
+              ],
+            },
+          },
+          'xcode_settings': {
+            'OTHER_CFLAGS': [
+              '-fprofile-arcs',
+              '-ftest-coverage',
+            ],
+          },
+        },
+    }],
+  ],
+}
+