* Hide the tooltip initially.
* Fix a bug with routing.
* Further separate the Slider model and view, refactoring its code.
* More reliance on events than direct calls between areas.
* Smarter background diff loading (single mode). Loads the diffs closest to your position first.
* Removed a bunch of manual templating and `render()` methods. Now relies more on the WP Backbone Views functionality.
* include the requested `id` in `ensure:load`.
* new trigger: `ensure`, for `ensure()` attempts, regardless of whether they are already loaded.
* pass along a promise in both `ensure` and `ensure:load`.
* in `ensure`, remove requests for diffs we aready have
See #24425.
git-svn-id: https://develop.svn.wordpress.org/trunk@24671 602fd350-edb4-49c9-b593-d223f7449a82
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