Hide it by overlaying it with our fake scrollbar. Remove explicit wheel handling
for reasons of being extremely hard to get right.

Issue #694

Issue #698

Issue #698

And move browser detection up in the codemirror.js file, to prevent
further instances of 'use sniffing before actually doing it' bugs.

Closes #692

That'll make getElementById fail to return our measure element,
which shouldn't break the whole editor anymore now.

To prevent problems with script concatenation.

Closes #684

This fixes an error in the case that extra properties have been added to
the array prototype.

Closes #679

Issue #676

Issue #674

Issue #650

They could get into an infinite recursion on Safari, causing
scrolling glitches.

It used to use stringWidth, which ignored transformations applied to
the text (most notably, tab replacement), and produced bad results.

Closes #672

Closes #671

Closes #670