[HD Pg 152, Sec. 6.3.0 - the-break-statement]

[enthunoob]

"This is called “fall through” behavior of a switch statement.
In absence of a break statement, the control falls through to the next case block and the next case block, and so on until it reaches the end of the switch statement. This feature is used when... "

Are you sure it's not just a bug?

[admin]

It is not unintentional behavior. That is how it is designed to work. Perks of being the language designer!