Bug 930162: NPE in TabMenuStrip. [r=lucasr, a=lsblakk]

mobile/android/base/home/TabMenuStrip.java

@@ -104,6 +104,10 @@ public class TabMenuStrip extends LinearLayout
 
         setScrollingData(position, positionOffset);
 
+        if (fromTab == null || toTab == null) {
+            return;
+        }
+
         final int fromTabLeft =  fromTab.getLeft();
         final int fromTabRight = fromTab.getRight();