fix IE10 issue for disableOthers

[jetfontanilla]

Description

in IE10, the variable list for disableOthers returns "permission denied"
this causes an uncaught exception which breaks the rest of the javascript execution

issue described in #4378

Specific Changes proposed

directly invoking list[i].id triggers the permission denied error
however, if an object has all of its properties denied access to, Object.keys returns a length of 0

Requirements Checklist

• [ x ] Feature implemented / Bug fixed
• If necessary, more likely in a feature request than a bug fix
  • Change has been verified in an actual browser (Chome, Firefox, IE)
  • Unit Tests updated or fixed
  • Docs/guides updated
  • Example created (starter template on JSBin)
• Reviewed by Two Core Contributors

[gkatsev]

Hey @JetLogs. Thanks for the PR. This fix doesn't seem bad but I would like to have more background on why and when it's occurring? Would you be able to make a reduced test case? What type of source are you playing? In most of my testing, I can't get this to fail.

[jetfontanilla]

Hi,

it looks like this issue is happening when IE10 restricts access to an object's properties so acessing them directly causes an exception.
If I have to take a guess, this might have been caused by loading a media file that's cross-domain (like a CDN for in our use case)