Add regression test for stab display in doc blocks

Author: GuillaumeGomez

tests/rustdoc-gui/src/test_docs/lib.rs

@@ -20,10 +20,10 @@ Also, stop using `bar` as it's <span class="stab deprecated" title="">deprecated
 Also, stop using `bar` as it's <span class="stab deprecated" title="">deprecated</span>.
 Also, stop using `bar` as it's <span class="stab deprecated" title="">deprecated</span>.
 
-Finally, you can use `quz` only on <span class="stab portability"><code>Unix or x86-64</code>
-</span>.
-Finally, you can use `quz` only on <span class="stab portability"><code>Unix or x86-64</code>
-</span>.
+Finally, you can use `quz` only on <span class="stab portability" data-span="1"><code>Unix or x86-64
+</code></span>.
+Finally, you can use `quz` only on <span class="stab portability" data-span="2"><code>Unix or x86-64
+</code></span>.
 */
 
 use std::convert::AsRef;

tests/rustdoc-gui/stab-in-doc.goml

@@ -0,0 +1,9 @@
+// This test ensure that `stab` elements if used in doc blocks are not breaking the text layout.
+go-to: "file://" + |DOC_PATH| + "/test_docs/index.html"
+// We make the window wide enough for the two stabs who are looking into to be on the same line.
+set-window-size: (1100, 600)
+compare-elements-position: (
+    ".top-doc .docblock span[data-span='1']",
+    ".top-doc .docblock span[data-span='2']",
+    ["y"],
+)