Remove unnecessary vars in StringCharBuffer
Uniformly keep the '$' at the end of module class names.

This removes some complexity of dealing with and without the
'$'s, depending on in what context they are used.
It also removes the IR constraint that module classes should
end in a '$' at all.
Remove typeof, in and instanceof from Scala ops.

Use the JS operators instead, and unbox the result.

This simplifies the IR by getting rid of 3 rarely used
operators. There will be no performance impact with unchecked
asInstanceOfs.
Use Int codes for JS unary and binary operators.

Instead of Strings.
Merge pull request #1372 from gzm0/cleanup

Remove unnecessary vars in StringCharBuffer
Merge pull request #1376 from sjrd/tweak-ir

Tweak IR
Fix #1377: Remove flakyness of JSEnv test

The timeout tests rely on timing which is inherently unrealiable. By
ensuring large enough intervals between (expected) events, we
hopefully can eliminate flakyness.

This commit increases intervals from the order of 1ms to 10ms.
Fix #1375: Don't propagate all Rhino load exceptions to JS
Merge pull request #1379 from gzm0/rhino-fixes

Rhino fixes
wip