Remove the duplicated Null

std/haxe/macro/Expr.hx

@@ -434,7 +434,7 @@ enum ExprDef {
 		Represents a `switch` expression with related cases and an optional.
 		`default` case if edef != null.
 	**/
-	ESwitch( e : Expr, cases : Array<Case>, edef : Null<Null<Expr>> );
+	ESwitch( e : Expr, cases : Array<Case>, edef : Null<Expr> );
 
 	/**
 		Represents a `try`-expression with related catches.