This revision modifies LocalAccessible::Name such that the function trims
non-breaking spaces from the beginning and end of accessible names. We already
compress all ASCII whitespace and trim it from the prefixes and suffixes of
accessible names - this change just extends that trimming to non-breaking spaces
for the exterior ends of the name string only. This revision implements a new
function, TrimNonBreakingSpaces, which does the trimming. Finally, this revision
removes five expected failures from the web platform tests.
Differential Revision: https://phabricator.services.mozilla.com/D203993
10c7a982bd