Add API test for hb_ot_color_get_color_layers

src/dump-emoji.cc

diff --git a/src/dump-emoji.cc b/src/dump-emoji.cc
index e6fddee..14376a8 100644
--- a/src/dump-emoji.cc
+++ b/src/dump-emoji.cc
@@ -91,7 +91,8 @@
 {
   unsigned int upem = hb_face_get_upem (face);
 
-  for (hb_codepoint_t gid = 0; gid < hb_face_get_glyph_count (face); ++gid)
+  unsigned glyph_count = hb_face_get_glyph_count (face);
+  for (hb_codepoint_t gid = 0; gid < glyph_count; ++gid)
   {
     unsigned int num_layers = hb_ot_color_get_color_layers (face, gid, 0, nullptr, nullptr, nullptr);
     if (!num_layers)

src/hb-ot-color.cc

diff --git a/src/hb-ot-color.cc b/src/hb-ot-color.cc
index f5d3d88..8d444ab 100644
--- a/src/hb-ot-color.cc
+++ b/src/hb-ot-color.cc
@@ -230,7 +230,7 @@
  * @HB_OT_COLOR_PALETTE_FLAG_FOR_LIGHT_BACKGROUND: flag indicating that the color palette is suitable for rendering text on light background.
  * @HB_OT_COLOR_PALETTE_FLAG_FOR_DARK_BACKGROUND: flag indicating that the color palette is suitable for rendering text on dark background.
  *
- * Since: REPLACEME
+ * Since: DONTREPLACEME
  */
 typedef enum { /*< flags >*/
   HB_OT_COLOR_PALETTE_FLAG_DEFAULT = 0x00000000u,

src/hb-ot-color.h

diff --git a/src/hb-ot-color.h b/src/hb-ot-color.h
index 0343e5e..62e873b 100644
--- a/src/hb-ot-color.h
+++ b/src/hb-ot-color.h
@@ -1,5 +1,7 @@
 /*
  * Copyright © 2016  Google, Inc.
+ * Copyright © 2018  Khaled Hosny
+ * Copyright © 2018  Ebrahim Byagowi
  *
  *  This is part of HarfBuzz, a text shaping library.
  *