Box3B recompute only on precise. Add _testStarted class.

src/testing/testing.ts

 // eslint-disable-next-line @typescript-eslint/naming-convention
 export function _testStart(): void {
     window.dispatchEvent(new Event('threepipe-test-started'))
+    document.body.classList.add('_testStarted')
 }

src/three/math/Box3B.ts

         // InstancedMesh has boundingBox = null, so it can be computed
         if ((object as IObject3D).boundingBox !== undefined) {
 
-            if (/* (object as IObject3D).boundingBox === null && */typeof (object as IObject3D).computeBoundingBox === 'function') {
+            if ((precise || (object as IObject3D).boundingBox === null) && typeof (object as IObject3D).computeBoundingBox === 'function') {
 
                 (object as IObject3D).computeBoundingBox!()