fix current tab has no webview bug

    http://b/issue?id=3214823
    setCurrentTab is called before setting the active tab in the UI
    this guarantees the active tab has a webview

Change-Id: I5d56c42be5a19389d7bc2cc0c41039bb90cc8478
diff --git a/src/com/android/browser/Controller.java b/src/com/android/browser/Controller.java
index 79fff3d..aabdb26 100644
--- a/src/com/android/browser/Controller.java
+++ b/src/com/android/browser/Controller.java
@@ -1903,10 +1903,9 @@
     }
 
     protected void setActiveTab(Tab tab) {
-        // Update the UI before setting the current tab in TabControl
-        // so the UI can access the old tab to switch over from
-        mUi.setActiveTab(tab);
         mTabControl.setCurrentTab(tab);
+        // the tab is guaranteed to have a webview after setCurrentTab
+        mUi.setActiveTab(tab);
     }
 
     protected void closeEmptyChildTab() {