Pass non-primitive types by const reference instead of value.

No real changes, just avoid the unnecessary copying and also make the
signatures more consistent by adding the apparently forgotten "&" in a couple
of places.

See #15893.

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@75657 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

include/wx/webview.h

@@ -237,8 +237,8 @@ class WXDLLIMPEXP_WEBVIEW wxWebViewEvent : public wxNotifyEvent
 {
 public:
     wxWebViewEvent() {}
-    wxWebViewEvent(wxEventType type, int id, const wxString url,
-                   const wxString target)
+    wxWebViewEvent(wxEventType type, int id, const wxString& url,
+                   const wxString& target)
         : wxNotifyEvent(type, id), m_url(url), m_target(target)
     {}