Merge pull request #525 from scala-js/issue/524

Restore scalafix task to prePR

Author: japgolly

build.sbt

@@ -144,6 +144,11 @@ val prePR_nonCross = taskKey[Unit]("Performs all necessary work required before
 ThisBuild / prePR_nonCross := Def.sequential(
   root / clean,
   root / Compile / scalafmt,
-  root / Compile / compile,
+  Def.taskDyn {
+    if (scalaVersion.value.startsWith("2."))
+      (root / Compile / scalafix).toTask("")
+    else
+      Def.task[Unit]((root / Compile / compile).value)
+  },
   example / Compile / compile,
 ).value