js: Fix Javascript placement unit test
js: Fix Javascript placement unit test

Commit 3a2f5fcd renamed the `targetContainer` to `targetContainerID`,
but neglected to update the unit tests.

kklin/quilt,kklin/quilt,kelda/kelda,kklin/quilt,quilt/quilt,LuiseV/quilt,NetSys/quilt,LuiseV/quilt,NetSys/quilt,quilt/quilt,LuiseV/quilt,quilt/quilt,LuiseV/quilt,kklin/kelda,kklin/kelda,kelda/kelda,kelda/kelda,kklin/kelda,ejj/quilt-dev,ejj/quilt-dev,ejj/quilt-dev,quilt/quilt,kelda/kelda,NetSys/quilt,NetSys/quilt,kklin/quilt,LuiseV/quilt,kklin/kelda,ejj/quilt-dev,NetSys/quilt