allow constant expressions in if statements

common/src/test/resources/test.tesf

@@ -1,7 +1,7 @@
 test("hello", 1);
 test("ghgj{}()\"\\hgjhgj", 3.4);
 
-if(test("hello", 1) == test("hello", 1)) {
+if(test("hello", 1) == "a string literal") {
     test("hello", 1);
 }