Update documentation on `Record` and `identical`.

Smaller clean-ups.

CoreLibraryReviewExempt: Documentation only.
Change-Id: Idfe543f18927043ae8ec73e81dc7d9d333bb88df
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/294542
Reviewed-by: Erik Ernst <eernst@google.com>
Commit-Queue: Lasse Nielsen <lrn@google.com>

https://dart.googlesource.com/sdk/+/3e0ca136b6cd661affdb60f270ef27c0f9364c45

DEPS

diff --git a/DEPS b/DEPS
index 1f78d0f..f32cb01 100644
--- a/DEPS
+++ b/DEPS
@@ -245,7 +245,7 @@
 
   'engine/src/flutter': Var('flutter_git') + '/mirrors/engine' + '@' + '81a57d24e62a75558e8ea5e0b1a13bbbe513efc6',
 
-  'engine/src/third_party/dart': Var('dart_git') + '/sdk' + '@' + 'be6c10504a7907f22ac737cb193dd527ad30e146',
+  'engine/src/third_party/dart': Var('dart_git') + '/sdk' + '@' + '3e0ca136b6cd661affdb60f270ef27c0f9364c45',
 
   'flutter': Var('flutter_git') + '/mirrors/flutter' + '@' + '650901532183b06728fe4b4f1a1b049336856c76',
 

commits.json

diff --git a/commits.json b/commits.json
index d46481b..5261f33 100644
--- a/commits.json
+++ b/commits.json
@@ -1,5 +1,5 @@
 {
   "engine/src/flutter":"81a57d24e62a75558e8ea5e0b1a13bbbe513efc6",
-  "engine/src/third_party/dart":"be6c10504a7907f22ac737cb193dd527ad30e146",
+  "engine/src/third_party/dart":"3e0ca136b6cd661affdb60f270ef27c0f9364c45",
   "flutter":"650901532183b06728fe4b4f1a1b049336856c76"
 }
\ No newline at end of file