RST writer: treat Span as transparent.

Previously an Emph inside a Span was being treated as
nested markup and ignored.  With this patch, the Span
is just ignored.

Closes #5446.

1 files changed, 6 insertions, 0 deletions

diff --git a/test/command/5446.md b/test/command/5446.md
new file mode 100644
index 000000000..5b25c994b
--- /dev/null
+++ b/test/command/5446.md
@@ -0,0 +1,6 @@
+```
+% pandoc -f latex -t rst
+{\em test test \/}
+^D
+*test test*
+```