fix cues for IE and Edge

Created by: squarebracket

Using for (item in Object) is a bad idea in Microsoft browsers, as it'll pick up extraneous object properties. This causes some cues to be dropped, as it tries to create a new Cue from a function, which of course fails.

Corrected to C-style for loop.

You can test this by removing the call to attachTTMLRenderingDiv in the reference player.