🚮 Sweep experiments older than 2019-12-05

Sweep experiments last flipped globally up to 2019-12-05:

- (2018-07-23, ampproject#17012) `amp-access-iframe`: 1
- (2019-10-01, ampproject#24810) `amp-action-macro`: 1
- (2019-11-08, ampproject#25480) `amp-mega-menu`: 1
- (2019-11-13, ampproject#25516) `amp-nested-menu`: 1
- (2017-02-07, ampproject#7403) `amp-playbuzz`: 1
- (2019-10-21, ampproject#25170) `amp-sidebar-swipe-to-dismiss`: 1
- (2018-11-05, ampproject#19140) `amp-story-responsive-units`: 1
- (2018-07-11, ampproject#16678) `amp-story-v1`: 1
- (2018-07-11, ampproject#16678) `chunked-amp`: 1
- (2019-10-28, ampproject#25269) `fix-inconsistent-responsive-height-selection`: 0
- (2019-02-26, ampproject#21058) `fixed-elements-in-lightbox`: 1
- (2017-05-16, ampproject#9298) `pump-early-frame`: 1
- (2019-11-12, ampproject#25512) `swg-gpay-native`: 1

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**⚠️ This changes Javascript source files**

The following may contain errors and/or require intervention to remove superfluous conditionals:

- `extensions/amp-access/0.1/amp-access-source.js`
- `extensions/amp-access/0.1/test/test-amp-access-source.js`
- `extensions/amp-action-macro/0.1/amp-action-macro.js`
- `extensions/amp-action-macro/0.1/test/test-amp-action-macro.js`
- `extensions/amp-playbuzz/0.1/amp-playbuzz.js`
- `extensions/amp-playbuzz/0.1/test/test-amp-playbuzz.js`
- `extensions/amp-sidebar/0.1/amp-sidebar.js`
- `extensions/amp-sidebar/0.2/amp-sidebar.js`
- `extensions/amp-story/1.0/amp-story.js`
- `extensions/amp-story/1.0/test/test-amp-story.js`
- `src/runtime.js`
- `test/unit/test-runtime.js`

---

**⚠️ There are HTML files with possible references**

The following HTML files contain references to experiment names which may be stale and should be manually removed:

- `examples/playbuzz.amp.html`
- `examples/responsive-menu.amp.html`
- `examples/amp-action-macro.html`
- `examples/visual-tests/amp-mega-menu/amp-mega-menu-with-list.amp.html`
- `examples/visual-tests/amp-mega-menu/amp-mega-menu.amp.html`
- `test/manual/amp-mega-menu/amp-mega-menu-with-list.amp.html`
- `test/manual/amp-mega-menu/amp-mega-menu.amp.html`