Extend HashMapWithRefPtrAsKey WTF unit test

Extend HashMapWithRefPtrAsKey WTF unit test so that
it verifies that no unneeded argument referencing
happens.

Review URL: https://codereview.chromium.org/190663010

git-svn-id: svn://svn.chromium.org/blink/trunk@168899 bbb929c8-8fbe-4397-9dbb-9b2b20218538