Allow enabling WebSockets from Labs Preferences

Change-Id: Ia0dc06cbd4f2e8e340a8f8ee910a6310a5079d79

Conflicts:
	res/values/strings.xml
	res/xml-sw600dp/lab_preferences.xml
	res/xml/lab_preferences.xml
	src/com/android/browser/BrowserSettings.java
	src/com/android/browser/PreferenceKeys.java