Keep in mind Buffer.toString() still exists, but returns [object Object].
Reason for removal of Buffer.toString() was that it implicitly used
TextDecoder with fixed "utf-8" encoding and no way to customize
the encoding.
All Deno runtime test files were moved to cli/js/tests/ directory.
It makes a clear distinction that cli/js/tests/ contains code
that is run under Deno runtime as opposed to code in cli/js/ which
is used to create bundle and snapshot with "deno_typescript".
