clarify whether paused attribute reflects pausing of ancestor frames

[dbaron]

The explainer currently describes a frameElement.paused attribute, but isn't clear about whether this is true or false if an ancestor frame has been pause()d. It should probably be clear about which way this works.

I think there are arguments for both sides:

• reflecting state on ancestors makes it a better source of truth
• not reflecting state from ancestors makes it correspond better to the pause() and unpause() methods.

[dbaron]

(I got here from w3ctag/design-reviews#196.)

[jkarlin]

Agreed, thanks for your comments!

Going with true if an ancestor frame was paused as that way the developer can know if it can expect a frame to do work.