Make TR test infrastructure support being run from different directories.
Update stub
Adding fixed test mode and small examples for all diffs
fix compiler--validator mismatch on bitwise specializations
Make tc-l test cases give better error messages.
tweak bitwise-operation optimization

Recognize arguments that are variables bound to fixnums.
meta/new-web: gzip ".css" and ".js" on upload to S3

We assume that any web browser where ".css" or ".js" useful
can also handle gzipped content. Compress files that are
at least 1k.

Also, use the new "shallow" mode of s3-sync to speed updates
to download.racket-lang.org.
Adjust fixed mode and add new stlc counterexamples
add Michał Pałka's l
Fix description of citet requirements.
remove links synthesized information from drracket bug report
renumber poly-stlc bugs to start from 1
Misc cleanups to stlc and stlc-sub benchmarks:

 - add +
 - tweak definition of c to make more like Palka's dissertation
 - remove non-bugs from stlc-sub
 - share test suite between stlc and stlc-sub
Make TR class tests run successfully on their own

Closes PR 14409
add new stlc-sub bugs
unbreak stlc-sub test #9
redex: add virtual machine model to benchmark
change stlc-sub's 'check' function to not assume
its input is well-typed
add missing value production

also, use redex-check? instead of redex-check in 2 places
fix subst function

- its contract said it accepted M's as the third argument, but it
  worked only for v's
- remove two redundant cases