Add test case for Self:: links

Author: bugadani

src/test/rustdoc/intra-link-self-cache.rs

@@ -0,0 +1,14 @@
+#![crate_name = "foo"]
+// @has foo/enum.E1.html '//a/@href' '../foo/enum.E1.html#variant.A'
+
+/// [Self::A::b]
+pub enum E1 {
+    A { b: usize }
+}
+
+// @has foo/enum.E2.html '//a/@href' '../foo/enum.E2.html#variant.A'
+
+/// [Self::A::b]
+pub enum E2 {
+    A { b: usize }
+}