LibJS: Implement Infinity

Author: https://github.com/linusg
Commit: 543c6e00db
Pull-request: https://github.com/SerenityOS/serenity/pull/1584

Libraries/LibJS/Runtime/GlobalObject.cpp

@@ -18,7 +18,10 @@ GlobalObject::GlobalObject()
     put_native_function("gc", gc);
     put_native_function("isNaN", is_nan);
 
+    // FIXME: These are read-only in ES5
     put("NaN", js_nan());
+    put("Infinity", js_infinity());
+
     put("console", heap().allocate<ConsoleObject>());
     put("Date", heap().allocate<DateConstructor>());
     put("Error", heap().allocate<ErrorConstructor>());