jshint / jshint / 2451

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Pull #2927

travis-ci

[[FEAT]] Error for literals on rhs of `instanceof`

This patch adds a new parse error that is used when a literal or function
declaration is found on the right-hand side of the `instanceof` infix operator.
Specifically, it checks for number, string, object, array and regular expression
literals, as well as the null and undefined keywords and function declarations.

The following generate errors:

    x instanceof 0;
    x instanceof '';
    x instanceof null;
    x instanceof undefined;
    x instanceof {};
    x instanceof [];
    x instanceof /./;
    x instanceof function() {};
    x instanceof function MyUnusableFunction() {};

But this is okay:

    /x/ instanceof /x/.constructor;

as per GH-2773

References:

    Closes GH-2777

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