--- a/devtools/client/animationinspector/test/head.js
+++ b/devtools/client/animationinspector/test/head.js
@@ -375,17 +375,17 @@ function* changeTimelinePlaybackRate(pan
 function* waitForAnimationSelecting(panel) {
   yield panel.animationsTimelineComponent.once("animation-selected");
 }
 
 /**
  * Wait for rendering animation timeline.
  * @param {AnimationsPanel} panel
  */
-function* waitForAnimationTimelineRendering(panel) {
+function waitForAnimationTimelineRendering(panel) {
   return panel.animationsTimelineComponent.once("animation-timeline-rendering-completed");
 }
 
 /**
    + * Click the timeline header to update the animation current time.
    + * @param {AnimationsPanel} panel
    + * @param {Number} x position rate on timeline header.
    + *                 This method calculates