Fix: WKWebview Custom Protocol

[dr-bonez]

Description
In WKWebview (the webview for iOS), the Blob data type is not supported for non-http protocols. This can cause issues for custom browsers for iOS that use WKURLSchemeHandler. This change detects if the page is being hosted on a non-http URL scheme and will convert the Blob to an ArrayBuffer if so.

[o1egl]

@dr-bonez Can you please explain how the procol there could be non http(s)?

[dr-bonez]

Sure.
iOS is deprecating the UIWebview and replacing it with WKWebview. WKWebview will only let you override the transport protocol if you use a custom url scheme, so if a browser wants to do anything special with how requests are fetched, the page can't be accessed over http(s). For example, the Consulate browser for iOS uses a custom protocol (onion://) in order to use Tor as well as do network level caching.

[o1egl]

I think better would be to compare only prefix with startsWith.

[dr-bonez]

that would be more performant however not strictly correct in what we are trying to catch. Someone could theoretically use a custom protocol http+foo: and that would cause this to break, as it is then considered a "non-http protocol" from iOS's standpoint, but would be considered an http protocol from filebrowser's.