Bumping gaia.json for 6 gaia-central revision(s)

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https://hg.mozilla.org/integration/gaia-central/rev/78223101351b
Author: Rudy Lu <left.lu@gmail.com>
Desc: Merge pull request #11740 from RudyLu/3rdParty_keyboard_support_commit

Add 3rd-party keyboard support. r=timdream, evelyn

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https://hg.mozilla.org/integration/gaia-central/rev/2d3d66b6cb94
Author: Rudy Lu <left.lu@gmail.com>
Desc: Bug 906096 - Add some Gaia workaround to ensure the new IME framework continues to work in Firefox Nightly
r=timdream

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https://hg.mozilla.org/integration/gaia-central/rev/99503d4c8ce7
Author: Arthur Chen <crh0716@gmail.com>
Desc: Bug 856910, Bug 893557 -
1. Add Observable, ObservableArray, and ListView to Utils.
2. Add unit testing.
3. Implement the keyboard panel based on the UX spec.
r=evelyn

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https://hg.mozilla.org/integration/gaia-central/rev/cab563832974
Author: Arthur Chen <crh0716@gmail.com>
Desc: Bug 856910 - Add MVVM pattern in settings app. r=evelyn

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https://hg.mozilla.org/integration/gaia-central/rev/832be84f7767
Author: Rudy Lu <left.lu@gmail.com>
Desc: Bug 858383 - [Keyboard] Integrate the new keyboard manager with switch
and show layout list functions in Keyboard app.
 1. Modify keyboard manifest to expose entry points as input methods.
 2. Modify keyboard init logic to interact with new keyboard manager.
 3. Make use of inputContext in keyboard app.
 4. Bug 885692 - To integrate with the new keyboard switching API. for keyboard app
 5. Bug 899073 - inputContext.geText() whould return Promise
r=timdream

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https://hg.mozilla.org/integration/gaia-central/rev/a40a420ac1d1
Author: mpizza <mmm198219@gmail.com>
Desc: Bug 816912 - Keyboard Manager to support 3rd-party keyboard
    1. manage running keyboard layouts in System app
    2. generat new mozSettings array for keyboard app, setLayoutEnable
and saveToSettings fn in keyboard helper.
    3. keyboard helper will send 'keyboardsrefresh' event when
'mozSettings' change.
    4. Bug 885692 - To integrate with the new keyboard switching API. for km
    5. Bug 902830 - Use new chrome event for keyboard manager.
r=timdream