Merge pull request scala#4573 from backuitist/ticket/9253

SI-9253 avoid IndexOutOfBoundsException in TypeMaps.correspondingTypeArgument

Author: SethTisue

src/reflect/scala/reflect/internal/tpe/TypeMaps.scala

@@ -561,7 +561,7 @@ private[internal] trait TypeMaps {
                |  tparams  ${rhsSym.typeParams map own_s mkString ", "}
                |"""
 
-        if (argIndex < 0)
+        if (!rhsArgs.isDefinedAt(argIndex))
           abort(s"Something is wrong: cannot find $lhs in applied type $rhs\n" + explain)
         else {
           val targ   = rhsArgs(argIndex)