rustdoc: remove blank unstable spans

src/librustdoc/html/render.rs

@@ -3483,10 +3483,6 @@ fn item_struct(w: &mut fmt::Formatter, cx: &Context, it: &clean::Item,
                        ns_id = ns_id,
                        name = field.name.as_ref().unwrap(),
                        ty = ty)?;
-                if let Some(stability_class) = field.stability_class() {
-                    write!(w, "<span class='stab {stab}'></span>",
-                        stab = stability_class)?;
-                }
                 document(w, cx, field)?;
             }
         }

src/test/rustdoc/stability.rs

@@ -0,0 +1,12 @@
+#![feature(staged_api)]
+
+#![unstable(feature = "test", issue = "0")]
+
+pub struct Unstable {
+    // @has stability/struct.Unstable.html \
+    //      '//div[@class="stability"]//div[@class="stab unstable"]' \
+    //      'This is a nightly-only experimental API'
+    // @count stability/struct.Unstable.html '//span[@class="stab unstable"]' 0
+    pub foo: u32,
+    pub bar: u32,
+}