Bug 1735769 [wpt PR 31233] - Remove the `test_obj` parameter from the structured...

Bug 1735769 [wpt PR 31233] - Remove the `test_obj` parameter from the structured clone tests, a=testonly

Automatic update from web-platform-tests
Remove the `test_obj` parameter from the structured clone tests

The `test_obj` parameter in the comparison functions of the structured
clone battery of tests doesn't seem to be used at all, considering that
the those functions only use it to call `test_obj.done()`, which is a
no-op. This seems to have once been used to indicate asynchronous test
completion, but that hasn't worked for a long time, and #31232 has now
made that obsolete.

Aside from removing the `test_obj` arguments to the comparison functions
and the calls to `test_obj.done()`, as well as the creation of the
`testObjMock` object in the `check` function, this change also removes
the `callback_is_async` boolean argument to `compare_Array` and
`compare_Object`.

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wpt-commits: 8cc54d621755b2ea75f2391475a63934819e52df
wpt-pr: 31233