Need a wait handle on ExceptionInfo

[alexrp]

Otherwise there's no sane way to wait for the type name and message to load.

[jstedfast]

Well, what we should really do is get rid of ObjectValue.GetChild() and instead just use ObjectValue.GetChildren() and then we can wait on that (see the debugger unit tests for GetAllChildrenSync() extension method).

Then from there, look for the Message property, etc.