[javascript] fix test_ajax.js implementation
In cubicweb.ajax.js, we maintain two lists (cw.loaded_src and cw.loaded_href)
to keep track of already included CSS and JS. (see discussion about
jQuery and $('foo').appendTo($head) in _loadAjaxHtmlHead.)
Since all tests are executed in the "same page", those two
variables need to be reinitialized before each test.
[MESSAGES CONTROL]
disable-msg = C0301
[VARIABLES]
# Enable / disable this checker
enable-variables = yes
additional-builtins = _, display_name
[BASIC]
required-attributes=
attr-rgx = (w|[a-z_][a-z0-9_]{2,30})
variable-rgx = (w|[a-z_][a-z0-9_]{2,30})$
argument-rgx = (w|[a-z_][a-z0-9_]{2,30})$
[TYPECHECK]
generated-members=debug,info,notice,warning,error,critical,exception