loadNative method
Loads a native ad per spec.
Implementation
@override
Future<NativeHandle> loadNative(NativeLoadSpec spec) async {
await _checkLoadAllowed('native', spec.adUnitId);
loadLog.add('native:${spec.adUnitId}');
nativeSpecs.add(spec);
final handle = FakeNativeHandle(spec.adUnitId);
natives.add(handle);
return handle;
}