This code tries to be an implementation of ECMAScript 4, as available at http://www.mozilla.org/js/language/ Note that ES4 is still in the process of standardization.
It is meant to behave like an ES4 interpreter in strict mode, none of the backward-compatible braindead-isms like newline semicolon insertion and other stuff will ever be implemented.
This is the list of its shortcomings:
exceptions
namespaces,packages
constness
Number/String constructor and class methods
real regexp's
the methods listed in FIXME's (js_library.cc js_value.cc)