Eliminate a bit of silly indirection in automaticallyNotifiesObserver…

…sForKey

`self.sharedSchema` on an accessor class goes through an extra few steps of
trying to register it in the shared schema, discovering that it's a generated
class, and then returning the correct thing largely by coincidence. Fix this by
calling `sharedSchema` directly on the parent class.

Realm/RLMObjectBase.mm

@@ -333,7 +333,7 @@ + (BOOL)automaticallyNotifiesObserversForKey:(NSString *)key {
     const char *className = class_getName(self);
     const char accessorClassPrefix[] = "RLM:Managed";
     if (!strncmp(className, accessorClassPrefix, sizeof(accessorClassPrefix) - 1)) {
-        if (self.sharedSchema[key]) {
+        if ([class_getSuperclass(self.class) sharedSchema][key]) {
             return NO;
         }
     }