From 168b89ee7194febd5a40afd00813630e84c237f4 Mon Sep 17 00:00:00 2001
From: Paul Berry <paulberry@google.com>
Date: Fri, 22 Jan 2021 09:13:37 -0800
Subject: [PATCH] Remove workarounds now that type promotion accounts for local
 boolean variables.

This change removes workarounds that were introduced prior to landing
Dart language feature
https://github.com/dart-lang/language/issues/1274, which allows type
promotion in null safe code to account for local boolean variables.
The workarounds ensured that the code would analyze the same
regardless of whether the feature was enabled, allowing for a smoother
transition.  Now that the feature has fully landed, the workarounds
aren't needed anymore.
---
 lib/web_ui/lib/src/engine/html/surface.dart        | 12 +-----------
 lib/web_ui/lib/src/engine/semantics/semantics.dart | 10 ----------
 2 files changed, 1 insertion(+), 21 deletions(-)

diff --git a/lib/web_ui/lib/src/engine/html/surface.dart b/lib/web_ui/lib/src/engine/html/surface.dart
index b01ecbde7fb..d1d816d29c4 100644
--- a/lib/web_ui/lib/src/engine/html/surface.dart
+++ b/lib/web_ui/lib/src/engine/html/surface.dart
@@ -1092,17 +1092,7 @@ abstract class PersistedContainerSurface extends PersistedSurface {
       for (int indexInOld = 0; indexInOld < oldChildCount; indexInOld += 1) {
         final PersistedSurface? oldChild = oldChildren[indexInOld];
         final bool childAlreadyClaimed = oldChild == null;
-        // After https://github.com/dart-lang/language/issues/1274 is
-        // implemented, `oldChild` will be promoted to non-nullable on the RHS
-        // of the `||`, so we won't need to null check it (and it will cause a
-        // build failure to try to do so).  Until then, we need to null check it
-        // in such a way that won't cause a build failure once the feature is
-        // implemented.  We can do that by casting to `dynamic`, and then
-        // relying on the call to `canUpdateAsMatch` implicitly downcasting to
-        // PersistentSurface.
-        // TODO(paulberry): remove this workaround once the feature is
-        // implemented.
-        if (childAlreadyClaimed || !newChild.canUpdateAsMatch(oldChild as dynamic)) {
+        if (childAlreadyClaimed || !newChild.canUpdateAsMatch(oldChild)) {
           continue;
         }
         allMatches.add(_PersistedSurfaceMatch(
diff --git a/lib/web_ui/lib/src/engine/semantics/semantics.dart b/lib/web_ui/lib/src/engine/semantics/semantics.dart
index 7a3df9c5b76..36d05104066 100644
--- a/lib/web_ui/lib/src/engine/semantics/semantics.dart
+++ b/lib/web_ui/lib/src/engine/semantics/semantics.dart
@@ -875,16 +875,6 @@ class SemanticsObject {
         effectiveTransformIsIdentity = effectiveTransform.isIdentity();
       }
     } else if (!hasIdentityTransform) {
-      // After https://github.com/dart-lang/language/issues/1274 is implemented,
-      // `transform` will be promoted to non-nullable so we won't need to null
-      // check it (and it will cause a build failure to try to do so).  Until
-      // then, we need to null check it in such a way that won't cause a build
-      // failure once the feature is implemented.  We can do that using an
-      // explicit "if" test.
-      // TODO(paulberry): remove this check once the feature is implemented.
-      if (transform == null) { // ignore: unnecessary_null_comparison
-        throw 'impossible';
-      }
       effectiveTransform = Matrix4.fromFloat32List(transform);
       effectiveTransformIsIdentity = false;
     }