Add neg test

Author: smarter

tests/neg/i876.scala

@@ -0,0 +1,8 @@
+object Test {
+  val a: Int = 1
+  implicit def foo(x: a.type): String = "hi"
+  val b: Int = a
+
+  val x: String = a // ok
+  val y: String = b // error: found Int, required String
+}