This also updates node_tests to use new constructor which is uppercase,
and some properties that are changed to be more clear now, like
jsdom().defaultView which is meant to the window object is now called window.
Ref: https://github.com/jsdom/jsdom/blob/master/Changelog.md
This run_test helper sets up a convention that allows
us to give really short tracebacks for errors, and
eventually we can have more control over running
individual tests. (The latter goal has some
complications, since we often intentionally leak
setup in tests.)
This reverts commit 6e048c5d3f.
See #8963 for the main issue we need to fix before re-enabling this;
basically, some combination of toMarkdown and the way text/html gets
written was introducing a lot of bonus/bogus whitespace, both in the
form of newlines and spaces converted to ` `.