1443859 - Handle 'includeOnce' workaround for 'AllFramesAtDocument___.js' user scripts in webpack.config.js

Status: NEW

(Firefox for iOS :: General, enhancement, P3)

Description

[Justin D'Arcangelo [:justindarc]]

As a follow-up to Bug 1443538, our `includeOnce()` workaround for ensuring that the `AllFramesAtDocumentStart.js` and `AllFramesAtDocumentEnd.js` user scripts don't execute more than once should be extracted up to a single wrapper in `webpack.config.js` rather than having to check each individual module. This is an ugly workaround for the fact that WebKit seems to re-inject our `AllFramesAtDocument___.js` user scripts into certain frames multiple times. This behavior is especially prevalent in single-page applications like YouTube. Since some of these scripts add event listeners, we really need to safeguard this from happening until this no longer is an issue in WebKit or an alternative solution can be found.