Merge pull request #10962 from fernandojsg/clockdelta

First call to Clock.getDelta() should returns 0

src/core/Clock.js

@@ -47,6 +47,7 @@ Object.assign( Clock.prototype, {
 		if ( this.autoStart && ! this.running ) {
 
 			this.start();
+			return 0;
 
 		}