[vm/ffi] Fix test sizeOf struct on arm32

Bug introduced in https://dart-review.googlesource.com/c/sdk/+/182262.

See documentation on alignment in the following places:
- pkg/vm/lib/transformations/ffi.dart
- runtime/vm/compiler/ffi/abi.cc
- runtime/vm/compiler/ffi/native_type.cc

Closes: #44835

Change-Id: I114dd4286e559bb230e1ee27ae5cfd8a0b0d2927
Cq-Include-Trybots: luci.dart.try:vm-precomp-ffi-qemu-linux-release-arm-try,vm-ffi-android-debug-arm-try
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/182501
Commit-Queue: Daco Harkes <[email protected]>
Reviewed-by: Clement Skau <[email protected]>

Author: dcharkes

tests/ffi/sizeof_test.dart

@@ -16,9 +16,10 @@ get is64Bit => 8 == sizeOf<IntPtr>();
 void main() async {
   if (is32Bit) {
     Expect.equals(4, sizeOf<Pointer>());
-    Expect.equals(20, sizeOf<Coordinate>());
-  }
-  if (is64Bit) {
+    // Struct is 20 bytes on ia32 and arm32-iOS, but 24 bytes on arm32-Android
+    // and arm32-Linux due to alignment.
+    Expect.isTrue(20 == sizeOf<Coordinate>() || 24 == sizeOf<Coordinate>());
+  } else if (is64Bit) {
     Expect.equals(8, sizeOf<Pointer>());
     Expect.equals(24, sizeOf<Coordinate>());
   }

tests/ffi_2/sizeof_test.dart

@@ -16,9 +16,10 @@ get is64Bit => 8 == sizeOf<IntPtr>();
 void main() async {
   if (is32Bit) {
     Expect.equals(4, sizeOf<Pointer>());
-    Expect.equals(20, sizeOf<Coordinate>());
-  }
-  if (is64Bit) {
+    // Struct is 20 bytes on ia32 and arm32-iOS, but 24 bytes on arm32-Android
+    // and arm32-Linux due to alignment.
+    Expect.isTrue(20 == sizeOf<Coordinate>() || 24 == sizeOf<Coordinate>());
+  } else if (is64Bit) {
     Expect.equals(8, sizeOf<Pointer>());
     Expect.equals(24, sizeOf<Coordinate>());
   }