Remove manual overflow for JS arithmetic operations

libraries/stdlib/src/kotlin/collections/AbstractList.kt

@@ -123,7 +123,6 @@ public abstract class AbstractList<out E> protected constructor() : AbstractColl
             var hashCode = 1
             for (e in c) {
                 hashCode = 31 * hashCode + (e?.hashCode() ?: 0)
-                hashCode = hashCode or 0 // make sure we don't overflow
             }
             return hashCode
         }

libraries/stdlib/src/kotlin/collections/AbstractSet.kt

@@ -30,7 +30,7 @@ public abstract class AbstractSet<out E> protected constructor() : AbstractColle
         internal fun unorderedHashCode(c: Collection<*>): Int {
             var hashCode = 0
             for (element in c) {
-                hashCode = (hashCode + (element?.hashCode() ?: 0)) or 0
+                hashCode += (element?.hashCode() ?: 0)
             }
             return hashCode
         }