Restructure http/browser_client.dart in http package to avoid dart:mirrors usage (?)

[DartBot]

This issue was originally filed by @Scorpiion

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I'm not sure how much job is needed, but because of the new "dart2js mirrors policy" with the huge warning, it feels like it might be worth considering.

Is it a good idea (or even possible) to make so that the browser client don't depend on dart:mirrors? Or are users recommended to not use the http package on the client for a foreseeable future? (assuming most people would want to follow the instructions and try to avoid the dart2js warning)

Regards, Robert

[DartBot]

This comment was originally written by @Scorpiion

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To be clear, a simple Hello World app importing package:http/browser_client.dart gives this:

* Your app imports dart:mirrors via:

• main.dart => package:http => dart:mirrors

[lrhn]

Removed Type-Defect label.
Added Type-Enhancement, Pkg-Http, Area-Pkg, Triaged labels.

[nex3]

The warning sucks, but in practice the usage of mirrors in the http package is harmless. It's only used to determine that dart:io is unavailable, and adds essentially no size overhead to the compiled output.

I'd love to remove mirrors from the package, but right now the language just doesn't support it while maintaining the same API.

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Marked this as being blocked by #6943.

[DartBot]

This issue has been moved to dart-lang/http#25.