Enable more "File > open" tests (#145)

* Enable more "File > open" tests

When I added a `MemoryFileSystem`-based implementation of
`RandomAccessFile` in https://github.com/google/file.dart/pull/136,
I enabled `File > open` tests for `test/memory_test.dart` but did not
notice that various other tests depend on `MemoryFileSystem` and also
explicitly disabled them.

Enable them for `chroot_test.dart` and for `recording_test.dart`.
Enabling them for `replay_test.dart` currently does not work due to
other failures that I don't yet understand (see

* Fix type error when attempting to enable "File > open" replay tests

Fix `ReplayFile.read`/`readSync` to explicitly convert the input
(read from a JSON integer array) into a `Uint8List`.

Fixes one of the failures in https://github.com/google/file.dart/issues/144.

* Fix analysis error

* Disable "File > open" replay tests more selectively

Record/replay currently doesn't work with `RandomAccessFile.readInto`,
but we can enable other `RandomAccessFile` tests.
5 files changed