Migrate iOSContainerUtility

Summary: TSC actually found a type error here in `safeExec` which is nice.

Reviewed By: danielbuechele

Differential Revision: D16666740

fbshipit-source-id: 28a1ad12190d2351a48323f23c3a69947503625d

src/fb-stubs/ErrorReporter.tsx

@@ -16,8 +16,8 @@ import {ScribeLogger} from './ScribeLogger';
 export type ObjectError =
   | Error
   | {
-      message: string,
-      stack?: string,
+      message: string;
+      stack?: string;
     };
 
 export default class ErrorReporter {