Setup default font manager after engine created, to improve startup performance (#18225)

https://dart.googlesource.com/external/github.com/flutter/engine/+/89cf074d37633e030bb86a047f6e5bb49ef44b43
diff --git a/commits.json b/commits.json
index 6a18bda..1c470c8 100644
--- a/commits.json
+++ b/commits.json
@@ -1,5 +1,5 @@
 {
-  "external/github.com/flutter/engine":"c5d012900f7db0dc5dc9afb46f76d16b87915db0",
+  "external/github.com/flutter/engine":"89cf074d37633e030bb86a047f6e5bb49ef44b43",
   "external/github.com/flutter/flutter":"a1636b6fef2ebe7840ba6dc1b3f9d77095ef3b45",
   "sdk":"d6ec2530fd6015226a7957dda7499c2be156b174"
 }
\ No newline at end of file