Fix syntax error: "screen" is read-only (#3237)

src/deprecated/platformSpecificDeprecated.android.js

@@ -317,7 +317,7 @@ async function startTabBasedApp(params) {
   params.tabs.forEach(function(tab, idx) {
     if (tab.components) {
       const components = tab.components;
-      const screen = createBottomTabScreen(tab, idx, params)
+      let screen = createBottomTabScreen(tab, idx, params)
       const {label, icon} = screen;
       screen.screens = components.map(c => createBottomTabScreen({...c, icon, label}, idx, params));
       screen.screens.map((s, i) => addTitleBarBackButtonIfNeeded(s));