Rewrite temporary variable elimination

js/js.translator/testData/js-optimizer/temporary-variable/nonSideEffect.optimized.js

@@ -0,0 +1,10 @@
+function foo(x) {
+    return x;
+}
+
+function box() {
+    var result = foo(2) + 1;
+    if (result != 3) return "fail: " + result;
+    
+    return "OK";
+}