[subset] Avoid incorrectly dropping cmap for NotoColorEmoji.ttf

NotoColorEmoji.ttf uses two cmap subtables

 Format 14 | Platform ID 0 | Platform Encoding ID  5
 Format 12 | Platform ID 3 | Platform Encoding ID 10

This combination results in the cmap table being dropped during subsetting despite being valid/required.

src/hb-ot-cmap-table.hh

@@ -1225,7 +1225,7 @@ struct cmap
       else if (_.platformID == 3 && _.encodingID == 10) ms_ucs4 = table;
     }
 
-    if (unlikely (!unicode_bmp && !ms_bmp)) return_trace (false);
+    if (unlikely (!has_format12 && !unicode_bmp && !ms_bmp)) return_trace (false);
     if (unlikely (has_format12 && (!unicode_ucs4 && !ms_ucs4))) return_trace (false);
 
     auto it =

test/api/test-subset-cmap.c

@@ -133,6 +133,48 @@ test_subset_cmap_empty_tables (void)
   hb_face_destroy (face_empty);
 }
 
+static void
+test_subset_cmap_noto_color_emoji_noop (void)
+{
+  hb_face_t *face = hb_test_open_font_file ("fonts/NotoColorEmoji.cmap.ttf");
+
+  hb_set_t *codepoints = hb_set_create ();
+  hb_face_t *face_subset;
+  hb_set_add (codepoints, 0x38);
+  hb_set_add (codepoints, 0x39);
+  hb_set_add (codepoints, 0xAE);
+  hb_set_add (codepoints, 0x2049);
+  hb_set_add (codepoints, 0x20E3);
+  face_subset = hb_subset_test_create_subset (face, hb_subset_test_create_input (codepoints));
+  hb_set_destroy (codepoints);
+
+  hb_subset_test_check (face, face_subset, HB_TAG ('c','m','a','p'));
+
+  hb_face_destroy (face_subset);
+  hb_face_destroy (face);
+}
+
+static void
+test_subset_cmap_noto_color_emoji_non_consecutive_glyphs (void)
+{
+  hb_face_t *face = hb_test_open_font_file ("fonts/NotoColorEmoji.cmap.ttf");
+  hb_face_t *face_expected = hb_test_open_font_file ("fonts/NotoColorEmoji.cmap.38,AE,2049.ttf");
+
+  hb_set_t *codepoints = hb_set_create ();
+  hb_face_t *face_subset;
+  hb_set_add (codepoints, 0x38);
+  hb_set_add (codepoints, 0xAE);
+  hb_set_add (codepoints, 0x2049);
+  face_subset = hb_subset_test_create_subset (face, hb_subset_test_create_input (codepoints));
+  hb_set_destroy (codepoints);
+
+  hb_subset_test_check (face_expected, face_subset, HB_TAG ('c','m','a','p'));
+
+  hb_face_destroy (face_subset);
+  hb_face_destroy (face_expected);
+  hb_face_destroy (face);
+}
+
 // TODO(rsheeter) test cmap to no codepoints
 
 int
@@ -145,6 +187,8 @@ main (int argc, char **argv)
   hb_test_add (test_subset_cmap_non_consecutive_glyphs);
   hb_test_add (test_subset_cmap4_no_exceeding_maximum_codepoint);
   hb_test_add (test_subset_cmap_empty_tables);
+  hb_test_add (test_subset_cmap_noto_color_emoji_noop);
+  hb_test_add (test_subset_cmap_noto_color_emoji_non_consecutive_glyphs);
 
   return hb_test_run();
 }

test/subset/data/tests/cmap14.tests

@@ -1,5 +1,6 @@
 FONTS:
 cmap14_font1.otf
+cmap14_font2.otf
 
 PROFILES:
 default.txt