Add a test with Scala.js 1.0.0.

sbt-crossproject-test/src/sbt-test/new-api/scalajs-1.0.0/build.sbt

@@ -0,0 +1,9 @@
+scalaVersion in ThisBuild := "2.12.10"
+
+lazy val bar =
+  crossProject(JSPlatform, JVMPlatform)
+    .crossType(CrossType.Pure)
+    .in(file("."))
+    .jsSettings(
+      scalaJSUseMainModuleInitializer := true
+    )

sbt-crossproject-test/src/sbt-test/new-api/scalajs-1.0.0/project/scalajs1x.sbt

@@ -0,0 +1 @@
+addSbtPlugin("org.scala-js" % "sbt-scalajs" % "1.0.0")

sbt-crossproject-test/src/sbt-test/new-api/scalajs-1.0.0/src/main/scala/sbttest/Main.scala

@@ -0,0 +1,14 @@
+package sbttest
+
+object Main {
+  def main(args: Array[String]): Unit = {
+    println("Hello")
+    val vmVersion = System.getProperty("java.vm.version")
+    println(vmVersion)
+
+    val isScalaJS = 1.0.toString() == "1"
+    println(s"isScalaJS = $isScalaJS")
+    if (isScalaJS)
+      assert(vmVersion == "1.0.0")
+  }
+}

sbt-crossproject-test/src/sbt-test/new-api/scalajs-1.0.0/test

@@ -0,0 +1,3 @@
+> barJVM/run
+> barJS/run
+> barJS/testHtml