[ffi] Remove a test that relies on not-Null Safe subtyping

This CL does not clean up the null checks that are discussed in
#47486

Change-Id: Iff5891d48dd9e0602940896001a7bb29538f6016
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/429620
Reviewed-by: Daco Harkes <[email protected]>
Commit-Queue: Chloe Stefantsova <[email protected]>

Author: chloestefantsova

tests/ffi/function_test.dart

@@ -36,7 +36,6 @@ void main() {
     testFloatRounding();
     testVoidReturn();
     testNoArgs();
-    testNativeFunctionNullableInt();
   }
 }
 
@@ -583,20 +582,3 @@ String get arg2ObfuscatedName {
   final str = (arg2: 0).toString();
   return str.substring('('.length, str.length - ': 0)'.length);
 }
-
-void testNativeFunctionNullableInt() {
-  final sumPlus42 = ffiTestFunctions
-      .lookupFunction<Int32 Function(Int32, Int32), int Function(int, int?)>(
-        "SumPlus42",
-      );
-
-  try {
-    sumPlus42(3, null);
-  } catch (e) {
-    // TODO(http://dartbug.com/47098): Save param names to dwarf.
-    Expect.isTrue(
-      e.toString().contains(arg2ObfuscatedName) ||
-          e.toString().contains('<optimized out>'),
-    );
-  }
-}