In ResourceLoaderContext, normalize invalid skin names to $wgDefaultSkin . This shoul...

In ResourceLoaderContext, normalize invalid skin names to $wgDefaultSkin . This should help a lot with the pollution of the module_deps table, which is currently littered with invalid skin names from people trying to hack the site. I found 3,897 (!!) distinct values for md_skin

Sample from the query result:

| md_module                   | md_skin                          |
|-----------------------------|----------------------------------|
| ext.vector.collapsibleNav   | vector'                          |
| ext.vector.collapsibleNav   | vector' and 1=1--                |
| ext.vector.collapsibleNav   | vector' and 1=2--                |
| ext.vector.collapsibleNav   | vector')waitfor delay'0:0:20'--  |
| ext.vector.collapsibleNav   | vector',0)waitfor delay'0:0:20'- |
| ext.vector.collapsibleNav   | vector',0,0)waitfor delay'0:0:20 |
| ext.vector.collapsibleNav   | vector',0,0,0)waitfor delay'0:0: |
| ext.vector.collapsibleNav   | vector'waitfor delay'0:0:20'--   |
| ext.vector.collapsibleNav   | vector../../../../../../../../.. |
[...]
| ext.vector.sectionEditLinks | vector<script src=               |
| ext.vector.sectionEditLinks | vector?.tri.co.id/               |
| ext.vector.sectionEditLinks | vector??id=jCustomerWAPProv      |
| ext.vector.sectionEditLinks | vector??id=wap.mauj.com....      |
| ext.vector.sectionEditLinks | vector?id=202.87.41.147....      |
| ext.vector.sectionEditLinks | vector?java                      |
| ext.vector.sectionEditLinks | vector?m.vuclip.com/             |
| ext.vector.sectionEditLinks | vector?toyota.co.id              |
| ext.vector.sectionEditLinks | vectorGET                        |
| ext.vector.sectionEditLinks | vector]]>>                       |
| ext.vector.sectionEditLinks | vector`ping -c 20 127.0.0.1`     |
| ext.vector.sectionEditLinks | vector|echo 9e7f7fd5750593ab cef |
| ext.vector.sectionEditLinks | vector|ping -c 20 127.0.0.1||x   |