[gtk] (14 commits) ...widget: Use gsk_transform_transform_point() in gtk_widget_pick()

[Timm Bäder <baedert src gnome org>]

Summary of changes:

  c8fa1f1... gl renderer: Transform rounded rect on the GPU (*)
  6852882... gl renderer: Move rect transformation to the vertex shader (*)
  d965267... cssimagerecolor: Implement is_computed() (*)
  d4caf3d... cssimagescaled: Implement is_computed() (*)
  aea27b8... cssimagepaintable: Implement is_computed() (*)
  7855a98... cssimageicontheme: Avoid copying colors (*)
  962e38c... gl renderer: Shorten shaders a bit (*)
  cff8304... GskTransform: Add gsk_transform_transform_point() (*)
  ab0869e... gl renderer: Add builder offset correctly for non-affine mo (*)
  ac4e98f... testsuite: Add test cases for last commit (*)
  8afdbd6... gl renderer: Make render_rounded_clip_node clearer (*)
  77f8245... gl renderer: Handle blur nodes with invisible children (*)
  f80a341... gl renderer: handle cross-fade nodes with invisible childre (*)
  8e41fa2... widget: Use gsk_transform_transform_point() in gtk_widget_p (*)

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