Multi-threading debugger support

We have been using jsd.dll to implement JavaScript debugging. When we run in 
a multi-thread environment in which we switch JS contextes between threads, 
we have been having lots of aborts in the debugger when destroying JSD 
contexts. Usually JS_GC fails in a free().

We noticed that JSDContext has a jsdc->dumbContext, but that there is no 
support for switching threads via  JS_SetContextThread() and 
JS_ClearContextThread(). This causes assertion failures in GC. Is this a 
bug? Should jsd work in such a mode? Could some calls be added to assign the 
thread to the context correctly?

Robin