SI-8229 Source compatible name for implicit any2stringadd

To support the established pattern for disabling it for
an compilation unit.

Update scaladoc's knowledge of our "typeclasses".

Leave a `private[scala]` version of `StringAdd` (public in bytecode)
to ensure binary compatibility with 2.11.0-M8 for partest.

1 files changed, 6 insertions, 0 deletions

diff --git a/test/files/neg/t8229.scala b/test/files/neg/t8229.scala
new file mode 100644
index 0000000000..91966311e2
--- /dev/null
+++ b/test/files/neg/t8229.scala
@@ -0,0 +1,6 @@
+import Predef.{any2stringadd => _, _}
+
+object Test {
+  val o = new Object()
+  o + ""
+}