Add Chrome to Dockerfile (#11210)

https://dart.googlesource.com/external/github.com/flutter/engine/+/a6cd477f543a863fc44803cf7db2e39a19ba97dd
diff --git a/commits.json b/commits.json
index 57616e2..d4a4d15 100644
--- a/commits.json
+++ b/commits.json
@@ -1,5 +1,5 @@
 {
-  "external/github.com/flutter/engine":"ca86f6d7e153a9d54d841c7c1fcb05ffe376dec4",
+  "external/github.com/flutter/engine":"a6cd477f543a863fc44803cf7db2e39a19ba97dd",
   "external/github.com/flutter/flutter":"e833a5820e798ad2e5920484b99a2d7bbb391460",
   "sdk":"38ca72a3e73781832cdc0773fd43348aa3bd4ec7"
 }
\ No newline at end of file