Roll engine to version 37779318019c397471751fe67ba0fefcd0d720d7

Includes the following changes :
377793180 Roll Dart to version eab492385c3f345cb2f44f3b702b0e30e4a9c107 (#5979)
8a7af11f7 Fix IsolateStart event kind. (#5978)
diff --git a/bin/internal/engine.version b/bin/internal/engine.version
index 9cf4309..8c35269 100644
--- a/bin/internal/engine.version
+++ b/bin/internal/engine.version
@@ -1 +1 @@
-78f8bcace79bd39d1dced3fd2280a3a1f9f25e0c
+37779318019c397471751fe67ba0fefcd0d720d7