From 624fc6a9d60c4551aeef361886424b7a306b1725 Mon Sep 17 00:00:00 2001
From: Nate Biggs <natebiggs@google.com>
Date: Thu, 9 Mar 2023 22:08:46 +0000
Subject: [PATCH] [dart2js] Remove as checks where the expression is known to
 be null and the cast type is nullable.

Change-Id: I3f17a581d77bf4cfda90cf931c4bbdf0a53d0929
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/286681
Commit-Queue: Nate Biggs <natebiggs@google.com>
Reviewed-by: Stephen Adams <sra@google.com>
---
 pkg/compiler/lib/src/ssa/nodes.dart | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/pkg/compiler/lib/src/ssa/nodes.dart b/pkg/compiler/lib/src/ssa/nodes.dart
index 1b27d2ca69d..76eb335fc50 100644
--- a/pkg/compiler/lib/src/ssa/nodes.dart
+++ b/pkg/compiler/lib/src/ssa/nodes.dart
@@ -4344,6 +4344,8 @@ AbstractBool _typeTest(
     if (expressionIsNull.isPotentiallyTrue) {
       if (dartType.isObject) return AbstractBool.Maybe;
     }
+  } else if (expressionIsNull.isDefinitelyTrue && _nullIs(dartType)) {
+    return AbstractBool.True;
   }
 
   if (checkedAbstractValue.isPrecise &&