Array.prototype.splice polyfill for Opera

Apparently they can't get their basic ECMAScript right. In 2013.

It doesn't come up that often, because you don't splice an array with
more than 256 elements every day. Only implemented in ve.batchSplice
for now, as that function does handle thousands of elements routinely.
Other callers of .splice() can simply use that instead.

Bug: 50385
Change-Id: I281a61d55c6f7df5f28627a1df80f2a001110607
Merge "Array.prototype.splice polyfill for Opera"