swf: Remove `impl Default for FunctionFlags`

Simply use `FunctionFlags::empty()` directly.

swf/src/avm1/types.rs

@@ -143,7 +143,7 @@ impl<'a> From<DefineFunction<'a>> for DefineFunction2<'a> {
             name: function.name,
             register_count: 0,
             params,
-            flags: FunctionFlags::default(),
+            flags: FunctionFlags::empty(),
             actions: function.actions,
         }
     }
@@ -169,12 +169,6 @@ bitflags! {
     }
 }
 
-impl Default for FunctionFlags {
-    fn default() -> Self {
-        Self::empty()
-    }
-}
-
 #[derive(Clone, Debug, Eq, PartialEq)]
 pub struct GetUrl<'a> {
     pub url: &'a SwfStr,