Upgrade to Scala 2.13.0-M4.

Jenkinsfile

@@ -389,7 +389,7 @@ def allJavaVersions = otherJavaVersions.clone()
 allJavaVersions << mainJavaVersion
 
 def mainScalaVersion = "2.12.5"
-def mainScalaVersions = ["2.10.2", "2.11.12", "2.12.5", "2.13.0-M3"]
+def mainScalaVersions = ["2.10.2", "2.11.12", "2.12.5", "2.13.0-M3", "2.13.0-pre-a52482c"]
 def otherScalaVersions = [
   "2.10.3",
   "2.10.4",

ci/checksizes.sh

@@ -17,6 +17,9 @@ case $FULLVER in
   2.13.0-M3)
     VER=2.13.0-M3
     ;;
+  2.13.0-pre-a52482c)
+    VER=2.13.0-pre-a52482c
+    ;;
   2.10.3|2.10.4|2.10.5|2.10.6|2.10.7|2.11.0|2.11.1|2.11.2|2.11.4|2.11.5|2.11.6|2.11.7|2.11.8|2.11.11|2.12.0|2.12.1|2.12.2|2.12.3|2.12.4)
     echo "Ignoring checksizes for Scala $FULLVER"
     exit 0
@@ -60,6 +63,12 @@ case $FULLVER in
     REVERSI_PREOPT_GZ_EXPECTEDSIZE=77000
     REVERSI_OPT_GZ_EXPECTEDSIZE=33000
     ;;
+  2.13.0-pre-a52482c)
+    REVERSI_PREOPT_EXPECTEDSIZE=863000
+    REVERSI_OPT_EXPECTEDSIZE=206000
+    REVERSI_PREOPT_GZ_EXPECTEDSIZE=109000
+    REVERSI_OPT_GZ_EXPECTEDSIZE=49000
+    ;;
 esac
 
 echo "Checksizes: Scala version: $FULLVER"

ir/src/main/scala/org/scalajs/core/ir/Infos.scala

@@ -135,7 +135,7 @@ object Infos {
       this
     }
 
-    def addInterfaces(interfaces: TraversableOnce[String]): this.type = {
+    def addInterfaces(interfaces: Iterable[String]): this.type = {
       this.interfaces ++= interfaces
       this
     }

no-ir-check-test/src/test/scala/org/scalajs/testsuite/noircheck/DummyParentsTest.scala

@@ -7,14 +7,14 @@
 \*                                                                      */
 package org.scalajs.testsuite.noircheck
 
+import java.util.concurrent.ForkJoinWorkerThread
+
 import org.junit.Test
 
 class DummyParentsTest {
 
   @Test def linking_stages_should_provide_dummy_parents_if_required(): Unit = {
 
-    import scala.concurrent.forkjoin._
-
     // scala.concurrent.forkjoin.ForkJoinWorkerThread is not defined
     class DummyFJWorkerThread extends ForkJoinWorkerThread(null) {
       override def onStart(): Unit = { /* something */ }