Failure to emit a switch statement when default case has type annotation

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e.g.

   x match {
      case 1 | 2 | 3 => "foo";
      case (_ : Int) => "bar";
   }

will emit a series of comparisons rather than a switch.

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Imported From: https://issues.scala-lang.org/browse/SI-1452?orig=1
Reporter: @DRMacIver

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@DRMacIver said:
Note: This is because "isDefaultPattern" is unaware of the type of the match so has to assume that the type bound is unrelated to those being matched against.

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@paulp said:
Consolidated under #2398.