Bug 1026561 - The New Tab Page should be smarter about showing more tiles when on large screens [r=adw]

Bump up default columns to fit most Firefox users including 2560px wide resolutions.

browser/app/profile/firefox.js

@@ -1468,7 +1468,7 @@ pref("browser.newtabpage.enabled", true);
 pref("browser.newtabpage.rows", 3);
 
 // number of columns of newtab grid
-pref("browser.newtabpage.columns", 3);
+pref("browser.newtabpage.columns", 8);
 
 // directory tiles download URL
 pref("browser.newtabpage.directory.source", "chrome://global/content/directoryLinks.json");