Enable JIT by default for content (r=danderson).

modules/libpref/src/init/all.js

@@ -512,7 +512,7 @@ pref("javascript.enabled",                  true);
 pref("javascript.allow.mailnews",           false);
 pref("javascript.options.strict",           false);
 pref("javascript.options.relimit",          false);
-pref("javascript.options.jit.content",      false);
+pref("javascript.options.jit.content",      true);
 pref("javascript.options.jit.chrome",       false);
 
 // advanced prefs