LibJS: Remove Object(Object& prototype) footgun

This constructor was easily confused with a copy constructor, and it was
possible to accidentally copy-construct Objects in at least one way that
we dicovered (via generic ThrowCompletionOr construction).

This patch adds a mandatory ConstructWithPrototypeTag parameter to the
constructor to disambiguate it.

Userland/Libraries/LibJS/Runtime/Error.cpp

@@ -29,7 +29,7 @@ NonnullGCPtr<Error> Error::create(Realm& realm, DeprecatedString const& message)
 }
 
 Error::Error(Object& prototype)
-    : Object(prototype)
+    : Object(ConstructWithPrototypeTag::Tag, prototype)
 {
     populate_stack();
 }