Test that IDE can be started in CI

dotty-library-bootstrappedJS was broke, I fixed it but also removed all
js projects from IDE startup as explained in the comment.

Author: smarter

.drone.yml

@@ -40,7 +40,7 @@ steps:
   depends_on: [ clone ]
   commands:
   - cp -R . /tmp/2/ && cd /tmp/2/
-  - ./project/scripts/sbt ";dotty-bootstrapped/compile ;dotty-bootstrapped/test ;dotty-staging/test ;sjsSandbox/run;sjsSandbox/test;sjsJUnitTests/test"
+  - ./project/scripts/sbt ";dotty-bootstrapped/compile ;dotty-bootstrapped/test ;dotty-staging/test ;sjsSandbox/run;sjsSandbox/test;sjsJUnitTests/test ;configureIDE"
   - ./project/scripts/bootstrapCmdTests
 
 - name: community_build

project/Build.scala

@@ -54,6 +54,10 @@ object MyScalaJSPlugin extends AutoPlugin {
 
     // Typecheck the Scala.js IR found on the classpath
     scalaJSLinkerConfig ~= (_.withCheckIR(true)),
+
+    // Exclude all these projects from `configureIDE/launchIDE` since they
+    // take time to compile, print a bunch of warnings, and are rarely edited.
+    excludeFromIDE := true
   )
 }
 
@@ -760,7 +764,8 @@ object Build {
     settings(
       unmanagedSourceDirectories in Compile :=
         (unmanagedSourceDirectories in (`dotty-library-bootstrapped`, Compile)).value,
-      scalacOptions += "-Yerased-terms", // support declaration of scala.compiletime.erasedValue
+      scalacOptions in Compile :=
+        (scalacOptions in (`dotty-library-bootstrapped`, Compile)).value,
     )
 
   lazy val tastyCoreSettings = Seq(