Mixin: fix the initialization of traits

Before this commit, the following code:
trait Hello {
  println("Hello")
  val x: Int = 1
  println("World")
}

Became:
<trait> trait Hello extends Object {
  def <init>(): Hello = {
    {
      ()
    }
    this
  }
  <accessor> def x(): Int
  protected def initial$x(): Int = {
    println("Hello")
    1
  }
}

Notice that the initialization statements after the last getter were
missing, this is now fixed:
<trait> trait Hello extends Object {
  def <init>(): Hello = {
    {
      println("World")
      ()
    }
    this
  }
  <accessor> def x(): Int
  protected def initial$x(): Int = {
    println("Hello")
    1
  }
}

1 files changed, 13 insertions, 0 deletions

diff --git a/tests/run/traitInit.scala b/tests/run/traitInit.scala
new file mode 100644
index 000000000..664fe4ce0
--- /dev/null
+++ b/tests/run/traitInit.scala
@@ -0,0 +1,13 @@
+trait Hello {
+  println("Hello")
+  val x: Int = 1
+  println("World")
+}
+
+class A extends Hello
+
+object Test {
+  def main(args: Array[String]): Unit = {
+    new A
+  }
+}