improve parser under "use strict" (#1836)

- `const` without value
- `delete` of expression
- redefining `arguments` or `eval`

extend `test/ufuzz.js`
- optionally generate "use strict"
- improve handling of test cases with syntax errors
- group IIFE generation
- generate bare anonymous functions
- workaround `console.log()` for `new function()`
- generate expressions with `this`


fixes #1810

test/input/invalid/delete.js

@@ -0,0 +1,14 @@
+function f(x) {
+    delete 42;
+    delete (0, x);
+    delete null;
+    delete x;
+}
+
+function g(x) {
+    "use strict";
+    delete 42;
+    delete (0, x);
+    delete null;
+    delete x;
+}