Check .length before accessing characters

[gaearon]

See comment here: #11457 (comment).

Although it seems very unlikely that someone would pass a one-character prop, the price (at least in versions of V8 in Chrome right now) is reported to be about 10x.

So we should check .length first and then do the comparison.

Please comment if you want to take this issue.
If somebody already commented, please let them finish it.

[xjlim]

@Gaeron I'd like to work on this.

[xjlim]

Although it seems very unlikely that someone would pass a one-character prop, the price (at least in versions of V8 in Chrome right now) is reported to be about 10x.

@gaearon Just curious, is this documented somewhere?