rustdoc: add support for type filters in arguments and generics

This makes sense, since the search index has the information in it,
and it's more useful for function signature searches since a
function signature search's item type is, by definition, some type
of function (there's more than one, but not very many).

src/tools/rustdoc-js/tester.js

@@ -79,11 +79,18 @@ function checkNeededFields(fullPath, expected, error_text, queryName, position)
             "foundElems",
             "original",
             "returned",
-            "typeFilter",
             "userQuery",
             "error",
         ];
-    } else if (fullPath.endsWith("elems") || fullPath.endsWith("generics")) {
+    } else if (fullPath.endsWith("elems") || fullPath.endsWith("returned")) {
+        fieldsToCheck = [
+            "name",
+            "fullPath",
+            "pathWithoutLast",
+            "pathLast",
+            "generics",
+        ];
+    } else if (fullPath.endsWith("generics")) {
         fieldsToCheck = [
             "name",
             "fullPath",