Insert implicit downcasts in kernel strong mode.

pkg/kernel/testcases/strong-mode/DeltaBlue.baseline.txt

Index: pkg/kernel/testcases/strong-mode/DeltaBlue.baseline.txt
diff --git a/pkg/kernel/testcases/strong-mode/DeltaBlue.baseline.txt b/pkg/kernel/testcases/strong-mode/DeltaBlue.baseline.txt
index f2735c64a51a808b4c3f1f266ddb9234117afde7..c19b44bad63bf339c91d9fceeb0d625c268f0f9f 100644
--- a/pkg/kernel/testcases/strong-mode/DeltaBlue.baseline.txt
+++ b/pkg/kernel/testcases/strong-mode/DeltaBlue.baseline.txt
@@ -1,7 +1,7 @@
-// dynamic is not a subtype of dart.core::int (DeltaBlue.dart:126:17)
-// dynamic is not a subtype of dart.core::int (DeltaBlue.dart:133:15)
-// dynamic is not a subtype of dart.core::int (DeltaBlue.dart:138:36)
-// dynamic is not a subtype of dart.core::int (DeltaBlue.dart:139:15)
+// dynamic is not a subtype of dart.core::int (DeltaBlue.dart:126:18)
+// dynamic is not a subtype of dart.core::int (DeltaBlue.dart:133:16)
+// dynamic is not a subtype of dart.core::int (DeltaBlue.dart:138:37)
+// dynamic is not a subtype of dart.core::int (DeltaBlue.dart:139:16)
 library;
 import self as self;
 import "dart:core" as core;