Roll Flutter Engine from 3a7aa01b0a7d to 3b6edee0f8f7 (4 revisions) (#140884)

https://github.com/flutter/engine/compare/3a7aa01b0a7d...3b6edee0f8f7

2024-01-03 98614782+auto-submit[bot]@users.noreply.github.com Reverts "Roll Dart SDK from 7e9f7eab80d3 to c5a75ac9057c (1 revision)" (flutter/engine#49491)
2024-01-03 skia-flutter-autoroll@skia.org Roll Skia from 4b16117e94b2 to a9db1213b179 (1 revision) (flutter/engine#49487)
2024-01-03 dnfield@google.com [Impeller] Allow multiple --runtime-stage-* parameters to impellerc (flutter/engine#49475)
2024-01-03 skia-flutter-autoroll@skia.org Roll Dart SDK from 7e9f7eab80d3 to c5a75ac9057c (1 revision) (flutter/engine#49478)

If this roll has caused a breakage, revert this CL and stop the roller
using the controls here:
https://autoroll.skia.org/r/flutter-engine-flutter-autoroll
Please CC rmistry@google.com,zra@google.com on the revert to ensure that a human
is aware of the problem.

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https://issues.skia.org/issues/new?component=1389291&template=1850622

Documentation for the AutoRoller is here:
https://skia.googlesource.com/buildbot/+doc/main/autoroll/README.md

bin/internal/engine.version

-3a7aa01b0a7de48ed84e529e2ba9b483667bd09d
+3b6edee0f8f7266c36354d23eff917c69981596d