Add the ZoomDensity support in the Browser.

Per Leland's requst, change "Set text size" to "Text size" and etc.
diff --git a/res/xml/browser_preferences.xml b/res/xml/browser_preferences.xml
index fdfa839..23618c5 100644
--- a/res/xml/browser_preferences.xml
+++ b/res/xml/browser_preferences.xml
@@ -29,6 +29,14 @@
                 android:dialogTitle="@string/pref_text_size_dialogtitle" />
 
         <ListPreference
+                android:key="default_zoom"
+                android:title="@string/pref_default_zoom"
+                android:defaultValue="MEDIUM"
+                android:entries="@array/pref_default_zoom_choices"
+                android:entryValues="@array/pref_default_zoom_values"
+                android:dialogTitle="@string/pref_default_zoom_dialogtitle" />
+
+        <ListPreference
                 android:key="default_text_encoding"
                 android:title="@string/pref_default_text_encoding"
                 android:defaultValue="@string/pref_default_text_encoding_default"