Multiple fixes to browser

- Ensure that clearing of the FLAG_DIM_BEHIND happens only once.
  Clearing FLAG_DIM_BEHIND window flag multiple time was causing
  unnecessary paint.
- Implement shouldDownloadFavicon API in Tab to optimize favicon
  download.

Change-Id: I8027565a29f2f1f6a2429a282c8727c6b4fe0d45
diff --git a/src/com/android/browser/NavigationBarPhone.java b/src/com/android/browser/NavigationBarPhone.java
index b07f035..a973c93 100644
--- a/src/com/android/browser/NavigationBarPhone.java
+++ b/src/com/android/browser/NavigationBarPhone.java
@@ -208,7 +208,7 @@
             mTabSwitcher.setVisibility(View.VISIBLE);
             mTabText.setVisibility(View.VISIBLE);
             if (mUiController != null) {
-                mUiController.setWindowDimming(0f);
+                mUiController.setWindowDimming(0.0f);
             }
             break;
         case StateListener.STATE_HIGHLIGHTED: