Add GUI test for clicking on non-toggle summary

Author: jsha

src/librustdoc/html/static/js/main.js

@@ -891,7 +891,7 @@ function hideThemeButtonState() {
             if (e.target.tagName != "SUMMARY") {
                 e.preventDefault();
             }
-        })
+        });
     });
 
     onEachLazy(document.getElementsByClassName("notable-traits"), function(e) {

src/test/rustdoc-gui/src/lib2/lib.rs

@@ -22,6 +22,8 @@ pub struct Foo {
 }
 
 impl Foo {
+    /// Some documentation
+    /// # A Heading
     pub fn a_method(&self) {}
 }
 

src/test/rustdoc-gui/toggle-click-deadspace.goml

@@ -0,0 +1,8 @@
+// This test ensures that clicking on a method summary, but not on the "[-]",
+// doesn't toggle the <details>.
+goto: file://|DOC_PATH|/test_docs/struct.Foo.html
+assert-attribute: (".impl-items .rustdoc-toggle", {"open": ""})
+click: "h4.code-header" // This is the position of "pub" in "pub fn a_method"
+assert-attribute: (".impl-items .rustdoc-toggle", {"open": ""})
+click: ".impl-items .rustdoc-toggle summary::before" // This is the position of "[-]" next to that pub fn.
+assert-attribute-false: (".impl-items .rustdoc-toggle", {"open": ""})