Add support for never type (#39)

samples/never.ts

@@ -0,0 +1,11 @@
+declare module nevertype {
+
+  export class RangeQuery {
+      never: never;
+
+      value(queryVal: string | number): string;
+
+      method(foo: never): Array<never>;
+  }
+
+}

samples/never.ts.scala

@@ -0,0 +1,20 @@
+
+import scala.scalajs.js
+import js.annotation._
+import js.|
+
+package importedjs {
+
+package nevertype {
+
+@js.native
+@JSGlobal("nevertype.RangeQuery")
+class RangeQuery extends js.Object {
+  var never: Nothing = js.native
+  def value(queryVal: String | Double): String = js.native
+  def method(foo: Nothing): js.Array[Nothing] = js.native
+}
+
+}
+
+}

src/main/scala/org/scalajs/tools/tsimporter/Importer.scala

@@ -322,6 +322,7 @@ class Importer(val output: java.io.PrintWriter) {
       case "string"    => TypeRef.String
       case "null"      => TypeRef.Null
       case "undefined" => TypeRef.Unit
+      case "never"     => TypeRef.Nothing
     }
   }
 }

src/main/scala/org/scalajs/tools/tsimporter/parser/TSDefParser.scala

@@ -282,7 +282,7 @@ class TSDefParser extends StdTokenParsers with ImplicitConversions {
     stringLit ^^ StringLiteral
 
   private val isCoreTypeName =
-    Set("any", "void", "number", "bool", "boolean", "string", "null", "undefined")
+    Set("any", "void", "number", "bool", "boolean", "string", "null", "undefined", "never")
 
   def typeNameToTypeRef(name: String): BaseTypeRef =
     if (isCoreTypeName(name)) CoreType(name)

src/main/scala/org/scalajs/tools/tsimporter/sc/Definitions.scala

@@ -298,6 +298,7 @@ object TypeRef {
   val Function = TypeRef(scala_js dot Name("Function"))
   val Unit = TypeRef(scala dot Name("Unit"))
   val Null = TypeRef(scala dot Name("Null"))
+  val Nothing = TypeRef(scala dot Name("Nothing"))
 
   object Union {
     def apply(types: List[TypeRef]): TypeRef =