Remove unnecessary TTX compile step

Use .ttx with components as input for emoji_builder.py

Originally the .ttx generated by add_glyphs.py was compiled to
a .ttf file so it could be fed to emoji_builder.py. Now we can
feed it a .ttx file and remove the compile step. This way the
original glyph names are preserved and we can start adding
PNGs for the components.

Makefile

@@ -209,11 +209,7 @@ endif
 %.ttx: %.ttx.tmpl $(ADD_GLYPHS) $(ALL_COMPRESSED_FILES)
 	@python $(ADD_GLYPHS) -f "$<" -o "$@" -d "$(COMPRESSED_DIR)" $(ADD_GLYPHS_FLAGS)
 
-%.ttf: %.ttx
-	@rm -f "$@"
-	ttx "$<"
-
-$(EMOJI).ttf: $(EMOJI).tmpl.ttf $(EMOJI_BUILDER) $(PUA_ADDER) \
+$(EMOJI).ttf: $(EMOJI).tmpl.ttx $(EMOJI_BUILDER) $(PUA_ADDER) \
 	$(ALL_COMPRESSED_FILES) | check_vs_adder
 	@python $(EMOJI_BUILDER) $(SMALL_METRICS) -V $< "$@" "$(COMPRESSED_DIR)/emoji_u"
 	@python $(PUA_ADDER) "$@" "$@-with-pua"

third_party/color_emoji/emoji_builder.py

@@ -475,6 +475,10 @@ By default they are dropped.
 
 	print()
 
+	if font_file.endswith(".ttx"):
+		font = ttx.TTFont()
+		font.importXML(font_file)
+	else:
 		font = ttx.TTFont(font_file)
 	print("Loaded font '%s'." % font_file)