Fix memory leak in NavScreen

Enhance mTabViews management on NavScreen by calling
remove function when necessary

Change-Id: Iaa20aea894d8f53d66c6bb30ae4abc76a7fee68f
diff --git a/src/com/android/browser/NavScreen.java b/src/com/android/browser/NavScreen.java
index d734923..b11cc4a 100644
--- a/src/com/android/browser/NavScreen.java
+++ b/src/com/android/browser/NavScreen.java
@@ -163,6 +163,7 @@
             } else {
                 mUiController.closeTab(tab);
             }
+            mTabViews.remove(tab);
         }
     }
 
@@ -233,6 +234,7 @@
                 public void onClick(View v) {
                     if (tabview.isClose(v)) {
                         mScroller.animateOut(tabview);
+                        mTabViews.remove(tab);
                     } else if (tabview.isTitle(v)) {
                         switchToTab(tab);
                         mUi.getTitleBar().setSkipTitleBarAnimations(true);