MovieClip advance not changing frames due to fps being undefined

[hiperbou]

Hello,
I'm using Ticker, to manually tick to my MovieClips. It happens that when a movieclip is a child of another that is not ticked, the timeline never updates. The function advance, searches for ancestor's framerate, but it the stage is never reached, so it ends with the fps variable being undefined and failing the test on the following line:

EaselJS/src/easeljs/display/MovieClip.js

Line 497 in e174f21

var t = (fps !== null && fps !== -1 && time !== null) ? time/(1000/fps) + this._t : 1;

It could be fixed, using a non-strict null comparision to handle the undefined value also.
var t = (fps != null && fps !== -1 && time !== null) ? time/(1000/fps) + this._t : 1;

I could do a pull request if required, but I rather know that this will not break something.