Adds test infrastructure for JS optimizer. Adds simple tests

js/js.translator/testData/js-optimizer/temporary-assignment/declaration.optimized.js

@@ -0,0 +1,20 @@
+function test(n) {
+    var result;
+    if (n >= 0) {
+        result = n;
+    }
+    else {
+        result = -n;
+    }
+    return result;
+}
+
+function box() {
+    var result = test(20)
+    if (result != 20) return "fail1: " + result;
+
+    result = test(-20)
+    if (result != 20) return "fail2: " + result;
+
+    return "OK"
+}