Rollup merge of #90530 - GuillaumeGomez:simplify-js-tester, r=notriddle
Rollup merge of #90530 - GuillaumeGomez:simplify-js-tester, r=notriddle

Simplify js tester a bit

r? `````@notriddle`````

aidancully/rust,aidancully/rust,aidancully/rust,graydon/rust,aidancully/rust,aidancully/rust,graydon/rust,graydon/rust,graydon/rust,aidancully/rust,graydon/rust,graydon/rust