Remove sync constellation -> embedder communication
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- [ ] These changes fix#22042 (github issue number if applicable).
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Change ML search engine to duckduckgo
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Shut down Servo when the ML app quits
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Shut down servo when shutting down the magic leap app.
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Reduce the amount of EGL buffer swapping the ML port is doing
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At the moment, we're swapping the EGL buffers every heartbeat, which produces a lot of flickering. We should only swap the buffers when needed.
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