Roll engine to pick up changes that allow 'flutter test --preview-dart-2' (#14185)

* Roll engine to pick up changes that allow 'flutter test --preview-dart-2'

* Pick up windows 'flutter test' fix
diff --git a/bin/internal/engine.version b/bin/internal/engine.version
index 15ae8ee..21b35e8 100644
--- a/bin/internal/engine.version
+++ b/bin/internal/engine.version
@@ -1 +1 @@
-3e49d8a81559e762fa72feb62591eebaa7c8e8e3
+e45eb692b11a961fb52278f359d6ca8e0ffa599f