Roll engine 1b2a2075a936..b0b19d6ce1d2 (1 commits) (#21948)

https://github.com/flutter/engine/compare/1b2a2075a936...b0b19d6ce1d2

git log 1b2a2075a936..b0b19d6ce1d2 --no-merges --oneline
b0b19d6ce Fix the frontend_server test (flutter/engine#6261)


The AutoRoll server is located here: https://autoroll.skia.org/r/flutter-engine-flutter-autoroll

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

If the roll is causing failures, please contact the current sheriff, who should
be CC'd on the roll, and stop the roller if necessary.

bin/internal/engine.version

-1b2a2075a9360364a0571d965254b90f26f790a9
+b0b19d6ce1d23a5ca766ecc08199df1e27028d43