Currently, ecma_op_get_prototype_from_constructor may return NULL
and the function didn't raise that exception.
Also optimize multiple assignment of prototype_obj_p and
multiple access of JERRY_CONTEXT (current_new_target) out.
This fixes https://github.com/jerryscript-project/jerryscript/issues/4463
JerryScript-DCO-1.0-Signed-off-by: Yonggang Luo luoyonggang@gmail.com