And they also do not have a thread/frame attached to them
That makes dynamic and synthetic values attached to them impossible to update - which, among other things, makes it impossible to properly display persistent variables of types that could have such dynamic/persistent values
Fix this by making it so that a ValueObject can control its constantness (hint: dynamic and synthetic values cannot be constant) and whether it wants to let itself be updated when an invalid thread is around
llvm-svn: 237504