Fix a missing Backbone import, leading to broken types.

Review Request #13586 — Created Feb. 28, 2024 and submitted — Latest diff uploaded




Spina 3.0 introduced a Result<T> = Backbone._Result<T> alias in
objects.ts, but it failed to import Backbone. This led to an
assumption that Backbone was a global type that should not be
interfered with, and thus renamed the Backbone type in the resulting
d.ts file tto Backbone$1.

This broke typing in some ways. Result<T> no longer had a type (since
it didn't know what Backbone._Result<T> was in this context), and the
difference between Backbone and Backbone$1 led to issues resolving
types of some attributes in subclasses of our base classes.

This change adds the missing import, fixing up the types.

Unit tests pass.

Verified this fixed typing issues in Ink.