Closure minification fails under Nashorn

[mamacdon]

Running 2.1.18 under Java 8+Nashorn with optimize=closure, minification fails with an error:

TypeError: Cannot read property "invoke" from undefined

It is caused by this code in jslib/rhino/optimize.js:

//Bind to Closure compiler, but if it is not available, do not sweat it.
try {
    // Try older closure compiler that worked on Java 6
    JSSourceFilefromCode = java.lang.Class.forName('com.google.javascript.jscomp.JSSourceFile').getMethod('fromCode', [java.lang.String, java.lang.String]);
} catch (e) {
    try {
        // Try for newer closure compiler that needs Java 7+
        JSSourceFilefromCode = java.lang.Class.forName('com.google.javascript.jscomp.SourceFile').getMethod('fromCode', [java.lang.String, java.lang.String]);
    } catch (e) {}
}

//Helper for closure compiler, because of weird Java-JavaScript interactions.
function closurefromCode(filename, content) {
    return JSSourceFilefromCode.invoke(null, [filename, content]); // <-- error happens here**
}

Under Nashorn, the calls to java.lang.Class.forName(...) throw, which cause an error on the indicated line.

[mamacdon]

Created pull request #823, which fixes the issue for me.