[ffigen] Fixing ffigen/objc CI (#2725)

Author: liamappelbe

pkgs/ffigen/test/native_objc_test/global_native_test.dart

@@ -52,8 +52,7 @@ void main() {
       globalObject = NSObject();
       final obj1raw = globalObject!.ref.pointer;
 
-      // TODO(https://github.com/dart-lang/native/issues/1435): Fix flakiness.
-      // expect(objectRetainCount(obj1raw), greaterThan(0));
+      expect(objectRetainCount(obj1raw), greaterThan(0));
 
       return obj1raw;
     }

pkgs/ffigen/test/native_objc_test/global_test.dart

@@ -54,8 +54,7 @@ void main() {
       lib.globalObject = NSObject();
       final obj1raw = lib.globalObject!.ref.pointer;
 
-      // TODO(https://github.com/dart-lang/native/issues/1435): Fix flakiness.
-      // expect(objectRetainCount(obj1raw), greaterThan(0));
+      expect(objectRetainCount(obj1raw), greaterThan(0));
 
       return obj1raw;
     }

pkgs/ffigen/test/native_objc_test/util.dart

@@ -98,7 +98,7 @@ int objectRetainCount(Pointer<ObjCObject> object) {
   // isValidObject broke due to a runtime update.
   // These constants are the ISA_MASK macro defined in runtime/objc-private.h.
   const maskX64 = 0x00007ffffffffff8;
-  const maskArm = 0x00000001fffffff8;
+  const maskArm = 0x0000000ffffffff8;
   final mask = Abi.current() == Abi.macosX64 ? maskX64 : maskArm;
   final clazz = Pointer<ObjCObject>.fromAddress(header & mask);
 

pkgs/objective_c/test/autorelease_test.dart

@@ -26,6 +26,7 @@ void main() {
         {
           final object = NSObject();
           pointer = object.ref.retainAndAutorelease();
+          expect(objectRetainCount(pointer), greaterThan(0));
         }
         doGC();
         expect(objectRetainCount(pointer), greaterThan(0));
@@ -45,6 +46,7 @@ void main() {
           {
             final object = NSObject();
             pointer = object.ref.retainAndAutorelease();
+            expect(objectRetainCount(pointer), greaterThan(0));
           }
           doGC();
           expect(objectRetainCount(pointer), greaterThan(0));

pkgs/objective_c/test/util.dart

@@ -59,7 +59,7 @@ int objectRetainCount(Pointer<ObjCObject> object) {
   // isValidObject broke due to a runtime update.
   // These constants are the ISA_MASK macro defined in runtime/objc-private.h.
   const maskX64 = 0x00007ffffffffff8;
-  const maskArm = 0x00000001fffffff8;
+  const maskArm = 0x0000000ffffffff8;
   final mask = Abi.current() == Abi.macosX64 ? maskX64 : maskArm;
   final clazz = Pointer<ObjCObject>.fromAddress(header & mask);