Update to latest async and collection

Avoid using `late final` without initializers on public fields.

Change-Id: I41e36eb7f72b62362b34f4cb3f32a0906c5f362d
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/164661
Auto-Submit: Nate Bosch <nbosch@google.com>
Reviewed-by: Nicholas Shahan <nshahan@google.com>
diff --git a/DEPS b/DEPS
index 5d510bd..04bcae2 100644
--- a/DEPS
+++ b/DEPS
@@ -66,7 +66,7 @@
 
   # Revisions of /third_party/* dependencies.
   "args_tag": "1.6.0",
-  "async_rev": "3fedad22c6940650526a86adebbf2872b81c2805",
+  "async_rev": "38ace5fa83697928d5f29911e346e6311dd00857",
   "bazel_worker_rev": "26680d5e249b249c7216ab2fed0ac8ed4ee285c5",
   "benchmark_harness_rev": "ec6b646f5443faa871e126ac1ba248c94ca06257",
   "boolean_selector_rev": "665e6921ab246569420376f827bff4585dff0b14",
@@ -76,7 +76,7 @@
   "charcode_rev": "4a685faba42d86ebd9d661eadd1e79d0a1c34c43",
   "chrome_rev" : "19997",
   "cli_util_tag" : "0.2.0",
-  "collection_rev": "65d3e58ee5289528ec280d361a67a631d65b3d7f",
+  "collection_rev": "52e219581f72a3eac013d6f5550c580962677425",
   "convert_rev": "c1b01f832835d3d8a06b0b246a361c0eaab35d3c",
   "crypto_rev": "f7c48b334b1386bc5ab0f706fbcd6df8496a87fc",
   "csslib_rev": "681a6603f86bbbe64e8af42d722aef63b028d241",