Make sure params have no name

jedi/inference/names.py

@@ -341,6 +341,9 @@ class _ParamMixin(object):
             return '**'
         return ''
 
+    def get_qualified_names(self, include_module_names=False):
+        return None
+
 
 class ParamNameInterface(_ParamMixin):
     api_type = u'param'

test/test_api/test_full_name.py

@@ -113,3 +113,9 @@ def test_os_path(Script):
 def test_os_issues(Script):
     """Issue #873"""
     assert [c.name for c in Script('import os\nos.nt''').complete()] == ['nt']
+
+
+def test_param_name(Script):
+    name, = Script('class X:\n def foo(bar): bar''').goto()
+    assert name.type == 'param'
+    assert name.full_name is None