Bug 708414 - Improve layout of about:home for top sites (r=mfinkle)

Don't rely on absolute margin values and apply proper layout rules instead.

mobile/android/base/resources/layout/abouthome_content.xml

@@ -14,7 +14,8 @@
                         android:isScrollContainer="false"
                         android:background="@drawable/abouthome_topsites_bg_repeat">
 
-            <ImageView android:layout_width="fill_parent"
+            <ImageView android:id="@+id/top_sites_top"
+                       android:layout_width="fill_parent"
                        android:layout_height="50dip"
                        android:gravity="fill"
                        android:background="@drawable/abouthome_bg_repeat"/>
@@ -28,8 +29,9 @@
             <TextView android:id="@+id/top_sites_title"
                       android:layout_width="fill_parent"
                       android:layout_height="wrap_content"
+                      android:layout_below="@id/top_sites_top"
                       android:layout_marginLeft="12dip"
-                      android:layout_marginTop="55dip"
+                      android:layout_marginTop="5dip"
                       android:textSize="12sp"
                       android:textColor="#000000"
                       android:textStyle="bold"