Automatic update from web-platform-testsUpdate the encoding IDL file (#9780) Also update the existing idlharness.js test to use it. wpt-commits: b202bbb5aa0d235b22bac11fe902eab1094ef9d2 wpt-pr: 9780 wpt-commits: b202bbb5aa0d235b22bac11fe902eab1094ef9d2 wpt-pr: 9780