function onRenderStart() {
        // Render may be triggered during input, but we only measure the following animation frame
        if (state.keydown === 2 /* EventPhase.Finished */ && state.input === 2 /* EventPhase.Finished */ && state.render === 0 /* EventPhase.Before */) {
            // Only measure the first render after keyboard input
            performance.mark('render/start');
            state.render = 1 /* EventPhase.InProgress */;
            queueMicrotask(markRenderEnd);
            /** Schedule Task B. See explanation in {@link recordIfFinished} */
            scheduleRecordIfFinishedTask();
        }
    }
Record the start of the animation frame performing the rendering.