Add failing test case demonstrating scala#2780

Author: smarter

tests/run/i2780/Base.java

@@ -0,0 +1,5 @@
+package bla;
+
+public class Base {
+  protected String foo = "";
+}

tests/run/i2780/Test.scala

@@ -0,0 +1,12 @@
+class Foo extends bla.Base {
+  class Inner {
+    println(foo)
+  }
+}
+
+object Test {
+  def main(args: Array[String]): Unit = {
+    val f = new Foo
+    new f.Inner
+  }
+}