Various native functions are not hidden from mirrors.

[rmacnak-google]

mirrors/invoke_natives_test: Crash

[rmacnak-google]

r35289

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Added Fixed label.

There is still a blacklist with cases where the VM throws uncatchable API errors:

  // These either cause the VM to segfault or throw uncatchable API errors.
  // TODO(15274): Fix them and remove from blacklist.
  'dart.io._IOService.dispatch',
  new RegExp(r'._RandomAccessFile.'),
  'dart.io._StdIOUtils._socketType',
  'dart.io._StdIOUtils._getStdioOutputStream',
  'dart.io._Filter.newZLibInflateFilter',
  'dart.io._Filter.newZLibDeflateFilter',
  'dart.io._FileSystemWatcher._listenOnSocket',
  'dart.io.SystemEncoding.decode',
  'dart.io.SystemEncoding.encode',
  'dart.core.StringBuffer.toString', /// emptyarray: ok

Added Triaged label.

[rmacnak-google]

r43053. Remainder is a bug in io not mirrors.

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Added Fixed label.