[FIXED SECURITY-67] Forbid CSS links in markup to be on the safe side.(cherry picked from commit 1e19eb3ece)

core/src/main/java/hudson/markup/MyspacePolicy.java

@@ -67,7 +67,6 @@ public class MyspacePolicy {
             tag("img",      "src",ONSITE_OR_OFFSITE_URL,
                             "hspace","vspace");
             tag("iframe",   "src");
-            tag("link",     "type","rel");
             tag("ul,ol,li,dd,dl,dt,thead,tbody,tfoot");
             tag("table",    "noresize");
             tag("td,th,tr");