Bug 1661587 - Assert if there is no native widget only when not in headless mode. r=morgan

Differential Revision: https://phabricator.services.mozilla.com/D88493

accessible/mac/RootAccessibleWrap.mm

@@ -9,6 +9,7 @@
 
 #include "mozRootAccessible.h"
 
+#include "gfxPlatform.h"
 #include "nsCOMPtr.h"
 #include "nsObjCExceptions.h"
 #include "nsIFrame.h"
@@ -40,8 +41,8 @@ void RootAccessibleWrap::GetNativeWidget(void** aOutView) {
       nsIWidget* widget = view->GetWidget();
       if (widget) {
         *aOutView = (void**)widget->GetNativeData(NS_NATIVE_WIDGET);
-        NS_ASSERTION(
-            *aOutView,
+        MOZ_ASSERT(
+            *aOutView || gfxPlatform::IsHeadless(),
             "Couldn't get the native NSView parent we need to connect the "
             "accessibility hierarchy!");
       }

accessible/mac/mozRootAccessible.mm

@@ -53,15 +53,9 @@ static id<mozAccessible, mozView> getNativeViewFromRootAccessible(
 - (id)moxUnignoredParent {
   NS_OBJC_BEGIN_TRY_ABORT_BLOCK_NIL;
 
-  if (!mParallelView)
-    mParallelView = (id<mozView, mozAccessible>)[self representedView];
-
-  if (mParallelView)
-    return [mParallelView
-        accessibilityAttributeValue:NSAccessibilityParentAttribute];
-
-  MOZ_ASSERT(mParallelView, "we're a root accessible w/o native view?");
-  return [super moxUnignoredParent];
+  // If there is no represented view (eg. headless), this will return nil.
+  return [[self representedView]
+      accessibilityAttributeValue:NSAccessibilityParentAttribute];
 
   NS_OBJC_END_TRY_ABORT_BLOCK_NIL;
 }