Comment 9 for bug 1591761

Those won't help here - this can only be enabled by passing a global flag to Chromium.

allowFileAccessFromFileUrls and allowUniversalAccessFromFileUrls are foot-guns - they're really dangerous options and we shouldn't be relying on them in any shipping code. We need to figure out a better way to run local HTML applications that doesn't depend on file URLs and doesn't use the webview (which is a poor fit for your use-case anyway)