Add Shim for Function.prototype.bind()

[execjosh]

This change fixes #10522 by adding a shim for Function.prototype.bind(), which can be an intermediate step until we get the native implementation from a newer WebKit.

[ariya]

Let's not "fake" the JavaScript environment to provide something which is native. I don't think this is good.

[execjosh]

@ariya: Thank you for having a look!

This was intended to curb new users' woes about Function.prototype.bind's absence until the Qt 5.0 implementation is complete. I'm pretty sure it's not intrusive (i.e., it doesn't clobber). I was hoping that it would help alleviate the burdon of repetitious explanation.

I was also thinking that it could just spit out a message on stderr once per session to the effect of "[INFO] Function.prototype.bind is a polyfill. Please read about it at so-and-so" to notify the user.

Just out of curiosity, what is so bad about providing shims/polyfills in the meantime? I'm not sure I understand the aversion... 😕

[ariya]

We don't really plan to release anything official till 2.0 is ready anyway (which will have bind).

Also, the idea of not having a fake implementation is quite simple. A lot of frameworks and apps will rely on a faithful implementation of bind. Unless we can guarantee that it's not going to break popular libraries, then it's a risky move. Getting the right shim under all circumstances can be trick (see e.g. https://gist.github.com/jussi-kalliokoski/978329) and we should not be in the business of providing temporary workarounds.

[execjosh]

Thank you for elaborating! I understand your points now :)