Limit the message length in the notification

Summary:
Before this diff the notification fired for crash reporter had the entire callstack as its message, which is actually not required and it also makes a UI not good.

This diff just limits the message length

BUG:

{F154537911}

Reviewed By: passy

Differential Revision: D14594189

fbshipit-source-id: 663710e3e80be4367d0cc2a532fd4aa312cc0c1e

flow-typed/npm/unicode-substring.js

@@ -0,0 +1,14 @@
+/**
+ * Copyright 2018-present Facebook.
+ * This source code is licensed under the MIT license found in the
+ * LICENSE file in the root directory of this source tree.
+ * @format
+ * @flow
+ */
+declare module 'unicode-substring' {
+  declare export default function unicodeSubstring(
+    baseString: string,
+    start: number,
+    end: number,
+  ): string;
+}