Add test to ensure the attributes position when js is disabled

src/test/rustdoc-gui/lib.rs

@@ -27,6 +27,11 @@ pub fn foo() {}
 /// Just a normal struct.
 pub struct Foo;
 
+impl Foo {
+    #[must_use]
+    pub fn must_use(&self) -> bool { true }
+}
+
 /// Just a normal enum.
 pub enum WhoLetTheDogOut {
     /// Woof!

src/test/rustdoc-gui/nojs-attr-pos.goml

+// Check that the attributes are well positioned when javascript is disabled (since
+// there is no toggle to display)
+javascript: false
+goto: file://|DOC_PATH|/struct.Foo.html
+assert: (".attributes", {"margin-left": "0px"})