Remove FileReader tests.

[Ms2ger]

As of https://github.com/w3c/web-platform-tests/pull/1596, these are all covered by wpt. In particular:

• FileReader-a-001-001.html: idlharness.html
• FileReader-a-002-001.html: tests nothing of consequence
• FileReader-a-003-001.html: idlharness.html
• FileReader-a-004-001.html: idlharness.html
• FileReader-a-005-001.html: idlharness.html
• FileReader-a-006-001.html: idlharness.html
• FileReader-a-007-001.html: idlharness.html
• FileReader-a-008-001.html: idlharness.html
• FileReader-a-009-001.html: idlharness.html
• FileReader-a-010-001.html: historical.html
• FileReader-a-011-001.html: historical.html
• FileReader-a-012-001.html: historical.html
• FileReader-a-013-001.html: idlharness.html
• FileReader-a-014-001.html: idlharness.html
• FileReader-a-015-001.html: idlharness.html
• FileReader-a-016-001.html: idlharness.html
• FileReader-a-017-001.html: idlharness.html
• FileReader-a-018-001.html: idlharness.html
• FileReader-a-019-001.html: idlharness.html
• FileReader-a-020-001.html: idlharness.html
• FileReader-a-021-001.html: idlharness.html
• FileReader-a-022-001.html: idlharness.html
• FileReader-a-023-001.html: idlharness.html
• FileReader-a-024-001.html: idlharness.html
• FileReader-a-025-001.html: idlharness.html
• FileReader-a-026-001.html: idlharness.html
• FileReader-a-027-001.html: idlharness.html
• FileReader-a-028-001.html: idlharness.html
• FileReader-a-029-001.html: idlharness.html
• FileReader-a-030-001.html: idlharness.html
• FileReader-a-031-001.html: idlharness.html
• FileReader-a-032-001.html: idlharness.html
• FileReader-a-033-001.html: fileReader.html
• FileReader-a-034-001.html: idlharness.html
• FileReader-a-035-001.html: filereader_result.html
• FileReader-a-036-001.html: idlharness.html
• FileReader-a-037-001.html: filereader_result.html
• FileReader-a-038-001.html: idlharness.html
• FileReader-a-039-001.html: idlharness.html
• FileReader-a-040-001.html: idlharness.html
• FileReader-a-041-001.html: filereader_error.html
• FileReader-a-042-001.html: idlharness.html
• FileReader-a-043-001.html: idlharness.html
• FileReader-a-044-001.html: idlharness.html
• FileReader-a-045-001.html: idlharness.html
• FileReader-a-046-001.html: FileReader-event-handler-attributes.html
• FileReader-a-047-001.html: FileReader-event-handler-attributes.html
• FileReader-a-048-001.html: idlharness.html
• FileReader-a-049-001.html: FileReader-event-handler-attributes.html
• FileReader-a-050-001.html: FileReader-event-handler-attributes.html
• FileReader-a-051-001.html: idlharness.html
• FileReader-a-052-001.html: FileReader-event-handler-attributes.html
• FileReader-a-053-001.html: FileReader-event-handler-attributes.html
• FileReader-a-054-001.html: idlharness.html
• FileReader-a-055-001.html: FileReader-event-handler-attributes.html
• FileReader-a-056-001.html: FileReader-event-handler-attributes.html
• FileReader-a-057-001.html: idlharness.html
• FileReader-a-058-001.html: FileReader-event-handler-attributes.html
• FileReader-a-059-001.html: FileReader-event-handler-attributes.html
• FileReader-a-060-001.html: idlharness.html
• FileReader-a-061-001.html: FileReader-event-handler-attributes.html
• FileReader-a-062-001.html: FileReader-event-handler-attributes.html
• FileReader-a-063-001.html: idlharness.html
• FileReader-a-064-001.html: same as 058
• FileReader-a-065-001.html: same as 059
• FileReader-a-066-001.html: same as 060
• FileReader-a-067-001.html: same as 061
• FileReader-a-068-001.html: same as 062
• FileReader-a-069-001.html: same as 063