[gtk] (8 commits) ...icon-browser: Add .sidebar style class in the main window

[Jakub Steiner <jimmac src gnome org>]

Summary of changes:

  8e81cbe... stacksidebar: Add missing .navigation-sidebar to the inner  (*)
  40f2b49... Adwaita: Make treeexpander styling generic (*)
  9828756... Adwaita: Move placessidebar-specific sizing from .navigatio (*)
  179fc68... Adwaita: Fix some sidebar sizing (*)
  bd0d75e... Adwaita: Make sidebar row styling better (*)
  61dcb68... Adwaita: Unify sidebar background-color (*)
  56eac4f... gtk-demo: Add .sidebar style class in the main window (*)
  3e996f6... icon-browser: Add .sidebar style class in the main window (*)

(*) This commit already existed in another branch; no separate mail sent