backing out changeset efcb617d1d3d because it caused the regression in bug 515661

mobile/app/mobile.js

@@ -318,7 +318,7 @@ pref("geo.wifi.uri", "https://www.google.com/loc/json");
 pref("geo.enabled", true);
 
 #ifdef WINCE
-pref("layout.css.devPixelsPerPx", "1");
+pref("layout.css.devPixelsPerPx", 1);
 #endif
 
 // content sink control -- controls responsiveness during page load