Add missing (and remove superfluous) 'explicit' from constructors.

webkit/tools/test_shell/test_webview_delegate_mac.mm

Index: webkit/tools/test_shell/test_webview_delegate_mac.mm
diff --git a/webkit/tools/test_shell/test_webview_delegate_mac.mm b/webkit/tools/test_shell/test_webview_delegate_mac.mm
index 197ad970e4db391affd5f8f9ea46d08234d509bd..eb0b67019d5a827ac5b66f440cd5fc7d366619c9 100644
--- a/webkit/tools/test_shell/test_webview_delegate_mac.mm
+++ b/webkit/tools/test_shell/test_webview_delegate_mac.mm
@@ -102,7 +102,7 @@ void TestWebViewDelegate::show(WebNavigationPolicy policy) {
 
   std::vector<WebMenuItem> items;
   for (size_t i = 0; i < popup_menu_info_->items.size(); ++i)
-    items.push_back(popup_menu_info_->items[i]);
+    items.push_back(WebMenuItem(popup_menu_info_->items[i]));
 
   int item_height = popup_menu_info_->itemHeight;
   double font_size = popup_menu_info_->itemFontSize;