test: Some "rtl" layout cleanups

Call `_set_direction` directly from `set_layout` instead of from
`assert_pixels`, so that test code can use `set_layout("rtl")` and
have it do the right thing.

Also, `_set_direction` only sets the direction of either the page or
the shell, but does it in a confusing way. Let's do it more directly.

test/common/testlib.py

@@ -152,7 +152,8 @@
         "name": "rtl",
         "theme": "light",
         "shell_size": [1920, 1200],
-        "content_size": [1680, 1130]
+        "content_size": [1680, 1130],
+        "direction": "rtl"
     },
 ]
 
@@ -957,12 +958,10 @@ def _set_emulated_media_theme(self, name: str):
             self.cdp.invoke("Emulation.setEmulatedMedia", features=[{'name': 'prefers-color-scheme', 'value': name}])
 
     def _set_direction(self, direction: str):
-        cur_frame = self.cdp.cur_frame
         if self.is_present("#shell-page"):
-            self.switch_to_top()
             self.set_attr("#shell-page", "dir", direction)
-        self.switch_to_frame(cur_frame)
-        self.set_attr("html", "dir", direction)
+        else:
+            self.set_attr("html", "dir", direction)
 
     def set_layout(self, name: str):
         layout = next(lo for lo in self.layouts if lo["name"] == name)
@@ -972,6 +971,7 @@ def set_layout(self, name: str):
             self._set_window_size(size[0], size[1])
             self._adjust_window_for_fixed_content_size()
             self._set_emulated_media_theme(layout["theme"])
+            self._set_direction(layout.get("direction") or "ltr")
 
     def _adjust_window_for_fixed_content_size(self):
         if self.eval_js("window.name").startswith("cockpit1:"):
@@ -1180,16 +1180,11 @@ def assert_pixels(self, selector: str, key: str,
             for layout in self.layouts:
                 if layout["name"] not in skip_layouts:
                     self.set_layout(layout["name"])
-                    if "rtl" in self.current_layout["name"]:
-                        self._set_direction("rtl")
                     self.assert_pixels_in_current_layout(selector, key, ignore=ignore,
                                                          mock=mock, sit_after_mock=sit_after_mock,
                                                          scroll_into_view=scroll_into_view,
                                                          wait_animations=wait_animations,
                                                          wait_delay=wait_delay)
-
-                    if "rtl" in self.current_layout["name"]:
-                        self._set_direction("ltr")
             self.set_layout(previous_layout)
 
     def assert_no_unused_pixel_test_references(self):