Revert "SI-8601 Don't treat int/long division, or arraylength, as dead-code"

This reverts commit ee611cd.

Author: adriaanm

src/compiler/scala/tools/nsc/backend/opt/DeadCodeElimination.scala

@@ -193,8 +193,6 @@ abstract class DeadCodeElimination extends SubComponent {
               moveToWorkListIf(necessary)
             case LOAD_MODULE(sym) if isLoadNeeded(sym) =>
               moveToWorkList() // SI-4859 Module initialization might side-effect.
-            case CALL_PRIMITIVE(Arithmetic(DIV | REM, INT | LONG) | ArrayLength(_)) =>
-              moveToWorkList() // SI-8601 Might divide by zero
             case _ => ()
               moveToWorkListIf(cond = false)
           }