Make all buttons (also those that are not by definition popupmenus) that have a menu expose the ShowMenu action (by making them mozPopupButtonAccessible instances under the hood). r=surkov, b=363082

accessible/src/mac/nsAccessibleWrap.h

@@ -95,6 +95,12 @@ class nsAccessibleWrap : public nsAccessible
     
     PRInt32 GetUnignoredChildCount(PRBool aDeepCount);
     
+    PRBool HasPopup () {
+      PRUint32 state = 0;
+      GetState(&state);
+      return (state & nsIAccessible::STATE_HASPOPUP);
+    }
+    
     // return this accessible's all children, adhering to "flat" accessibles by not returning their children.
     void GetUnignoredChildren(nsTArray<nsRefPtr<nsAccessibleWrap> > &aChildrenArray);
     virtual already_AddRefed<nsIAccessible> GetUnignoredParent();

accessible/src/mac/nsAccessibleWrap.mm

@@ -105,7 +105,14 @@ nsAccessibleWrap::GetNativeType ()
     case ROLE_PUSHBUTTON:
     case ROLE_SPLITBUTTON:
     case ROLE_TOGGLE_BUTTON:
+    {
+      // if this button may show a popup, let's make it of the popupbutton type.
+      if (HasPopup())
+        return [mozPopupButtonAccessible class];
+        
+      // regular button
       return [mozButtonAccessible class];
+    }
     
     case ROLE_CHECKBUTTON:
       return [mozCheckboxAccessible class];

accessible/src/xul/nsXULFormControlAccessible.cpp

@@ -208,7 +208,7 @@ nsFormControlAccessible(aNode, aShell)
 }
 
 /**
-  * Only one actions available
+  * Only one action available
   */
 NS_IMETHODIMP nsXULDropmarkerAccessible::GetNumActions(PRUint8 *aResult)
 {