Install polyfill when upgrade is not a function

[Jeroen-Veltmans]

Fixes #565

Also check if upgrade is a function in case it is only supported on later browsers than define and get.

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[stale]

This issue has been automatically marked as stale because it has not had recent activity. It will be closed if no further activity occurs. Thank you for your contributions.

[MattiasBuelens]

Our team is still affected by this bug.

@sorvell @justinfagnani Sorry to bother, but could you please take a look at this PR?

[justinfagnani]

edit: oops, wrong polyfill. I'll try to take a look.

[justinfagnani]

@MattiasBuelens may I ask what browsers you're running on?

[Jeroen-Veltmans]

@justinfagnani it's added as part of the ticket. We saw the issue on some smart TVs which use Chrome v56 and v63. According to browser compatibility Chrome versions 54-67 are affected and other platforms like Mac Safari versions 10.1-12.0 should also be affected as the define method is defined but the upgrade method not yet.