[gtk+] (15 commits) ...Fix up background-origin now that we correctly handle the background color

[Alexander Larsson <alexl src gnome org>]

Summary of changes:

  c9a3332... Add generation of private g-types for private headers (*)
  1a68aff... css: Add _gtk_css_parser_try_enum (*)
  3e24029... css: Parse enums with new case-insensitive helper (*)
  8fb4b13... css: Break out enum parse/print helper (*)
  2a42fad... css: Use enum parsing for background repeat style (*)
  d85aabe... Rename GTK_CSS_REPEAT_STYLE_NONE to GTK_CSS_REPEAT_STYLE_ST (*)
  91dcf40... css: Convert border style parsing to use enums (*)
  c276f53... Make computed value of border-width 0 if border-style none (*)
  34e1556... Add reftest to test border-style: none
  330fd3b... Add GtkCssArea enum
  8411f1a... Implement background-clip and background-origin
  d8d7c7c... Update background-area reftest for background-clip
  9fd4e95... Reftest background-origin with various background-clip valu
  75642d3... css: Always draw the bg color under the bg image
  db5e387... Fix up background-origin now that we correctly handle the b

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