Investigate custom source map filenames in development

[gaearon]

On mobile now but see this thread for context:

https://twitter.com/danbucholtz/status/813786323660210176

[bmeck]

xref: webpack/webpack#3603

[gaearon]

Tagging to revisit before 0.10.

[gaearon]

Maybe we can just use this line?
https://github.com/aspnet/JavaScriptServices/blob/3c2fd50e8fc843973282ac4bbd63b454234f87e5/templates/ReactSpa/webpack.config.js#L36

[gaearon]

Tagging for 0.9.1 because maybe the fix is super easy.

[Timer]

Should we consider this breaking? Do you think anyone is relying on the fact that it's webpack:///?
It could cause some confusion for people that regularly see that prefix in chrome dev tools or similar -- maybe a bad side effect for a patch update.

We could put it in 0.10.0 to be safe (I don't think it's too far out) ...

[gaearon]

I'm cool with this being in 0.10.0.

[gaearon]

We'll want to update these instructions if we change it: #1540
Also would be nice to investigate #1465 at the same time.