Misleading result from getStaticValue() on expressions that re-use Symbol()s

[ninevra]

Example:

const symbol = Symbol();
(symbol === symbol); // <--

The value of the expression on line 2 is true, but getStaticValue() returns {value: false}.

This is probably because the two recursive calls to getStaticValueR() (evaluating the left and right sides of the BinaryExpression) both invoke Symbol() and so both return different Symbols.

This could be resolved either by removing Symbol from callAllowed or by caching the static values of Identifiers encountered during recursion. However, the latter approach would still produce strange results if the user compared the returned static values of, for example, two different references to const symbol = Symbol();.