Roll Flutter Engine from 831da7e9dc3b to 45851af55bd6 (2 revisions) (#130814)

https://github.com/flutter/engine/compare/831da7e9dc3b...45851af55bd6

2023-07-18 zanderso@users.noreply.github.com Reset Dart VM optimization level to 2 (flutter/engine#43770)
2023-07-18 jonahwilliams@google.com [Impeller] Avoid inserting additional save layers based on clip configuration. (flutter/engine#43759)

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 bdero@google.com,rmistry@google.com,zra@google.com on the revert to ensure that a human
is aware of the problem.

To file a bug in Flutter: https://github.com/flutter/flutter/issues/new/choose

To report a problem with the AutoRoller itself, please file a bug:
https://bugs.chromium.org/p/skia/issues/entry?template=Autoroller+Bug

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

bin/internal/engine.version

-831da7e9dc3b8be5ba70f0976efb4a4f168bb3dd
+45851af55bd6066b7b912af0bdd5968830f7bd4b