remove outdated comment

[skip ci]

src/text/glyph.cpp

@@ -3,9 +3,6 @@
 namespace mbgl {
 
 // Note: this only works for the BMP
-// Note: we could use a binary lookup table to get averaged constant time lookups, however,
-// most of our lookups are going to be within the first 3 ranges listed here, so this is
-// likely faster.
 GlyphRange getGlyphRange(char32_t glyph) {
     unsigned start = (glyph/256) * 256;
     unsigned end = (start + 255);