prepack fails when a switch statement has duplicate expressions in case clauses

[a8m]

Code example:

switch (Math.floor(Math.random() * 10)) {
  case 1:console.log('1'); break;
  case 1:console.log('1'); break;
  default: console.log('other');
}

Output:

Invariant Violation: pushing false
This is likely a bug in Prepack, not your code. Feel free to open an issue on GitHub.
....

Link to prepack-repl

[NTillmann]

To address this...

1. A test in test/serializer/abstract should be created, similar to other tests in that directory.
2. The root cause of the issue needs to be addressed.

[a8m]

Closed via #1681