JS backend: tests for reflection support

js/js.translator/testData/callableReference/function/cases/extensionToPrimitive.kt

@@ -0,0 +1,7 @@
+// This test was adapted from compiler/testData/codegen/boxWithStdlib/callableReference/function/local/.
+package foo
+
+fun box(): String {
+    fun Int.is42With(that: Int) = this + 2 * that == 42
+    return if (16.(Int::is42With)(13)) "OK" else "Fail"
+}