Implement function destructuring argument support. (#3322)

Furthermore create unmapped arguments objects if a function has a non-simple argument.
A few destructuring pattern issues were fixed as well.

JerryScript-DCO-1.0-Signed-off-by: Zoltan Herczeg zherczeg.u-szeged@partner.samsung.com

tests/jerry/es2015/function-rest-parameter.js

@@ -78,3 +78,18 @@ assert (g2 () === 11);
 assert (g2 (1) === 3);
 assert (g2 (1, 2) === 3);
 assert (g2 (1, 2, 3) === 4);
+
+function args(a, ...b)
+{
+  assert(a === 1);
+  assert(arguments[0] === 1);
+
+  a = 5;
+
+  assert(a === 5);
+  assert(arguments[0] === 1);
+
+  assert(arguments[1] === 2);
+  assert(b[0] === 2)
+}
+args(1, 2);