Atomics: moves getReport and waitUntil into atomicsHelper.js; broad updates to all Atomics.wait tests

Ref gh-1531

Update RegExp tests for CharacterClassEscape \S

Intl.Locale: Update expectation for empty values for collation and numberingSystem.

The spec changed in https://github.com/tc39/proposal-intl-locale/pull/47.

The tests for calendar were already correct.

Update tests for String.prototype.matchAll

Update RegExp Unicode property escape tests per Unicode 11

GetTemplateObject with a unique template object

As per spec changes (https://github.com/tc39/proposal-string-matchall/pull/35), removed tests related to the removed IsRegExp call.
To prevent older implementations (not observing spec change) from passing, added a new test to verify the reduced number of observable calls to IsRegExp.

Also fix a misreference in `features` frontmatter.