Consistent American spelling of 'behavior' (#58016)

https://dart.googlesource.com/external/github.com/flutter/flutter/+/066c5def0a2c02be25316bc79e9be2d2263aa215
diff --git a/commits.json b/commits.json
index 03c55a3..406b83c 100644
--- a/commits.json
+++ b/commits.json
@@ -1,5 +1,5 @@
 {
   "external/github.com/flutter/engine":"af14d2adf0e0933703cdf885ff2361a8f3eef00c",
-  "external/github.com/flutter/flutter":"29736f6feab387b798ce17218fd1739efe2ef0d2",
+  "external/github.com/flutter/flutter":"066c5def0a2c02be25316bc79e9be2d2263aa215",
   "sdk":"4cf584d4fed719c121c58a44df3b1cb77d5ce145"
 }
\ No newline at end of file