Speed up cmap format 4 loading
From quadratic to linear. Sigh.
diff --git a/Lib/fontTools/ttLib/tables/_c_m_a_p.py b/Lib/fontTools/ttLib/tables/_c_m_a_p.py
index a356c3c..cde727b 100644
--- a/Lib/fontTools/ttLib/tables/_c_m_a_p.py
+++ b/Lib/fontTools/ttLib/tables/_c_m_a_p.py
@@ -666,7 +666,7 @@
gids = []
for i in range(len(startCode) - 1): # don't do 0xffff!
rangeCharCodes = list(range(startCode[i], endCode[i] + 1))
- charCodes = charCodes + rangeCharCodes
+ charCodes.extend(rangeCharCodes)
for charCode in rangeCharCodes:
rangeOffset = idRangeOffset[i]
if rangeOffset == 0: