LibJS: Remove GlobalObject::{set_,}associated_realm()

Author: https://github.com/linusg
Commit: dfb7588d30
Pull-request: https://github.com/SerenityOS/serenity/pull/15035
Reviewed-by: https://github.com/davidot

Userland/Libraries/LibJS/Runtime/GlobalObject.h

@@ -24,9 +24,6 @@ public:
 
     Console& console() { return *m_console; }
 
-    Realm* associated_realm();
-    void set_associated_realm(Realm&);
-
 private:
     virtual bool is_global_object() const final { return true; }
 
@@ -44,7 +41,6 @@ private:
     JS_DECLARE_NATIVE_FUNCTION(unescape);
 
     NonnullOwnPtr<Console> m_console;
-    WeakPtr<Realm> m_associated_realm;
 };
 
 inline GlobalObject* Shape::global_object() const