Single Frame MovieClip adjust

From #1048 - "I checked the FPS on LG TV and so it is done from 60 to 20. On a static image. After research, I found that in the advance method in MovieClip class there is a constant check to update the frame. I added a change to check if the MovieClip class total frame is equal to 1 to change it the mode of the MovieClip to a single frame. This increases performance back to 60 FPS." - LiorZar

Has been tested but keep an eye on it - @gskinner might want to double check it.

src/easeljs/display/MovieClip.js

@@ -509,6 +509,9 @@ this.createjs = this.createjs||{};
 		while ((o = o.parent) && fps === null) { if (o.mode === independent) { fps = o._framerate; } }
 		this._framerate = fps;
 
+		// adjusted by Dan Zen 3/27/21 for https://github.com/CreateJS/EaselJS/issues/1048
+		if (this.totalFrames <= 1) { return; }
+
 		// calculate how many frames to advance:
 		var t = (fps !== null && fps !== -1 && time !== null) ? time/(1000/fps) + this._t : 1;
 		var frames = t|0;