[gtk+] (19 commits) Non-fast-forward update to branch wip/baedert/symbolic-icons

[Timm Bäder <baedert src gnome org>]

The branch 'wip/baedert/symbolic-icons' was changed in a way that was not a fast-forward update.
NOTE: This may cause problems for people pulling from the branch. For more information,
please see:

 https://wiki.gnome.org/Git/Help/NonFastForward

Commits removed from the branch:

  58303c2... csstypes: Add GTK_CSS_AFFECTS_SYMBOLIC_ICON
  7e23bee... stylepropertyimpl: Use GTK_CSS_AFFECTS_SYMBOLIC_ICON
  f5aef4e... iconhelper: Safe whether the surface is symbolic
  76c72ea... iconhelper: Un-duplicate some code
  96f7b02... GtkImage: Don't always invalidate the icon helper
  1eab646... iconhelper: Don't invalidate unnecessarily
  88f3e65... Remove more unnecessary redraws
  ff35494... cssstylechange: Add helper function to print change

Commits added to the branch:

  339023d... Fix indentation (*)
  61307de... levelbar: Make discrete levelbars behave as before (*)
  56b1b08... Adwaita: darker background for popovers (*)
  e35e6ab... css: Properly convert em, ex and rem to pixels (*)
  5444442... css: Convert numbers with GTK's dpi (*)
  132abb8... css tests: Fix expected output (*)
  f2e08d3... css tests: Fix style tests (*)
  982da04... cssimageradial: Only emit one error for wrong position (*)
  0c12601... cssimageradial: Only allow at "<position>" after other prop (*)
  fe6d4cb... inspector: Drop type name from node list (*)
  e8fca5b... cssmatcher: Remove type argument from name matcher (*)
  d48d3b3... cssselector: Remove type references (*)
  6b93462... Remove more unnecessary redraws
  0f4b8d9... iconhelper: Un-duplicate some code
  a668c6f... cssstylechange: Add helper function to print change
  883fc47... csstypes: Add GTK_CSS_AFFECTS_SYMBOLIC_ICON
  efa27f5... stylepropertyimpl: Use GTK_CSS_AFFECTS_SYMBOLIC_ICON
  6b5afae... iconhelper: Save whether the surface is symbolic
  230d28f... Add and use gtk_icon_helper_invalidate_for_change

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