Strengthen js-mode indentation tests

Test not only that the indentation engine is idempotent but that it
will indent a file to the expected shape from scratch.

* test/lisp/progmodes/js-tests.el (js-tests--remove-indentation): New.
(js-deftest-indent): Extend test.
1 job for master in 63 minutes and 55 seconds (queued for 1 second)
Status Job ID Name Coverage
  Test
passed #8337
test-all

01:03:55