Add dotty to cross-build

Author: Philippus

.travis.yml

@@ -5,6 +5,7 @@ import: scala/scala-dev:travis/default.yml
 language: scala
 
 scala:
+  - 0.22.0-RC1
   - 2.11.12
   - 2.12.10
   - 2.13.1
@@ -16,6 +17,11 @@ env:
   - ADOPTOPENJDK=11    SCALAJS_VERSION=
 
 matrix:
+  exclude:
+    - scala: 0.22.0-RC1
+      env: ADOPTOPENJDK=8     SCALAJS_VERSION=0.6.32
+    - scala: 0.22.0-RC1
+      env: ADOPTOPENJDK=8     SCALAJS_VERSION=1.0.0
   include:
     - scala: 2.11.12
       env: ADOPTOPENJDK=8     SCALANATIVE_VERSION=0.3.9

project/plugins.sbt

@@ -11,3 +11,5 @@ addSbtPlugin("org.scala-js" % "sbt-scalajs" % scalaJSVersion)
 
 addSbtPlugin("org.portable-scala" % "sbt-scala-native-crossproject" % "1.0.0")
 addSbtPlugin("org.scala-native" % "sbt-scala-native" % scalaNativeVersion)
+
+addSbtPlugin("ch.epfl.lamp" % "sbt-dotty" % "0.4.0")