[Impeller] Add FAQ entries. (#54456)

Fixes https://github.com/flutter/flutter/issues/153120
https://dart.googlesource.com/external/github.com/flutter/engine/+/2f577d8e3fa20a1cd151c0d98ff385e3a4426af8

DEPS

diff --git a/DEPS b/DEPS
index 814fc20..4ca4890 100644
--- a/DEPS
+++ b/DEPS
@@ -280,7 +280,7 @@
 deps = {
   'engine/src': 'https://github.com/flutter/buildroot.git' + '@' + '6ef931b950d5b9477dba0e278b7006ae327e12f7',
 
-  'engine/src/flutter': Var('flutter_git') + '/mirrors/engine' + '@' + '40f2805c7f68bf78f8ea92d22a3400bfb4dd2b89',
+  'engine/src/flutter': Var('flutter_git') + '/mirrors/engine' + '@' + '2f577d8e3fa20a1cd151c0d98ff385e3a4426af8',
 
   'engine/src/flutter/third_party/dart': Var('dart_git') + '/sdk' + '@' + '849cab7be8053a60086066de44f10814a3edcc38',
 

commits.json

diff --git a/commits.json b/commits.json
index 0bd95ca..01ba6e5 100644
--- a/commits.json
+++ b/commits.json
@@ -1,5 +1,5 @@
 {
-  "engine/src/flutter":"40f2805c7f68bf78f8ea92d22a3400bfb4dd2b89",
+  "engine/src/flutter":"2f577d8e3fa20a1cd151c0d98ff385e3a4426af8",
   "engine/src/flutter/third_party/dart":"849cab7be8053a60086066de44f10814a3edcc38",
   "flutter":"6d3e3204223f414c6d57fc58ec11f5937f25898e"
 }
\ No newline at end of file