Roll Flutter from a4ec627 to e12d1a7 (3 revisions) (flutter#5267)

flutter/flutter@a4ec627...e12d1a7

2023-10-29 [email protected] Reland `coverableLineCache` optimisation (#136851) (flutter/flutter#137385)
2023-10-28 [email protected] Instrument RestorationBucket, _RouteEntry and DisposableBuildContext for leak tracking. (flutter/flutter#137477)
2023-10-28 [email protected] BannerPainter should dispatch creation and disposal events.  (flutter/flutter#137472)

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.ci/flutter_master.version

@@ -1 +1 @@
-a4ec6278b1a4545a33968b1bb736de4918dbde8e
+e12d1a798c4984c81de284bdef9ae6687624725f