Mark with targets as parameters

This fixes a bug where the targets of a `{% with %}` block would not
be marked as a parameter. This is because they were not being marked
at all as a variable which results in an invalid AST. For reference
counting purposes, this must also be marked specifically as a parameter
variable instead of as a stored variable to ensure it does not leak
out of the block.

new_parser.py

@@ -197,7 +197,7 @@ def parse_block_with(ast):
         if 'key' not in parameter:
             raise
 
-        targets.append(parameter['key'])
+        targets.append(nodes.Name(parameter['key'], 'param'))
         values.append(parse_variable(parameter['value']))
 
     with_node.targets = targets

test_template.jinja

@@ -1,8 +1,6 @@
 {% from 'forms.html' import input as input_field, textarea %}
 {{ dict_var['single']["double"].dot  |test("first" ,2_000, named=3.14)|filter | lastFilter}}
-{%with key=val %}
-test {{var}}
-{%endwith%}
+{% with a='', b=a.attribute %}...{% endwith %}
 {% for item in dict_var.values() %}
     <li>{% block loop_item %}{{ item }}{% endblock %}</li>
 {% endfor %}