Revert "~~JS parser: added jsExpression intrinsic"

This reverts commit 081dc9c96f776a080c6edfc43174ffaed08b8f34.
Revert "~~ prohibit using jsCode as expression, use jsExpression instead"

This reverts commit a40861b1f5d3ce11c59d32ff11a1e495c3edc3e8.
~~ removed removeQuotes method
~~ removed @author sections from JavaDoc

Otherwise JetConformanceTest failed.
Authors are listed at each file's header,so it's useless anyway.