COLRv0: remove duplicate CPAL palette to work around FireFox bug

[anthrotype]

In the current COLRv0 fonts, the CPAL palette index=4 and index=5 are duplicates (i.e. contain the same colors). I don't see why that would be a problem, besides being a waste of bytes.

However, for some strange reasons, these duplicate palettes somehow make FireFox (v104.0.1, as well as FF Nightly 106.0a1 (2022-09-01)) display the colors incorrectly, see the screenshot below. As far as I can tell, this particular combination of greys is not taken from any of the available CPAL palettes inside Bungee Color; it's as if FireFox is making things up, or simply giving up altogether, who knows..

Now, if I dump the fonts with ttx, remove the duplicate palette and then re-compile the fonts with ttx, then FireFox is happy again and shows the default red/white palette (at index=0). Whereas the additional or customized color palettes are not supported by FireFox yet, but only work in Chrome or Safari (see https://bugzilla.mozilla.org/show_bug.cgi?id=1461588).

This PR removes the duplicate palette so that the COLRv0 font works in FireFox as well as the rest of the browsers.

/cc @jfkthame from Mozilla as he may be interested to take a look too

[anthrotype]

This is the diff between the existing fonts and the modified ones from this PR (you can see I simply removed palette 5 and re-number the index of the following ones, going from 9 to 8 total palettes)

$ diff -Naur /Users/clupo/Github/Bungee/fonts/Bungee_Color_Fonts/COLRv0/BungeeColor-Regular_COLRv0_old.ttx /Users/clupo/Github/Bungee/fonts/Bungee_Color_Fonts/COLRv0/BungeeColor-Regular_COLRv0_new.ttx
--- /Users/clupo/Github/Bungee/fonts/Bungee_Color_Fonts/COLRv0/BungeeColor-Regular_COLRv0_old.ttx       2022-09-02 12:16:43.000000000 +0100
+++ /Users/clupo/Github/Bungee/fonts/Bungee_Color_Fonts/COLRv0/BungeeColor-Regular_COLRv0_new.ttx       2022-09-02 12:12:56.000000000 +0100
@@ -877,12 +877,12 @@
     <!-- Most of this table will be recalculated by the compiler -->
     <tableVersion value="1.0"/>
     <fontRevision value="1.0"/>
-    <checkSumAdjustment value="0x139aeb2f"/>
+    <checkSumAdjustment value="0x4c248fc1"/>
     <magicNumber value="0x5f0f3cf5"/>
     <flags value="00000000 00000001"/>
     <unitsPerEm value="1000"/>
     <created value="Tue Jun  7 11:21:57 2016"/>
-    <modified value="Wed May 25 20:16:42 2022"/>
+    <modified value="Fri Sep  2 11:06:12 2022"/>
     <xMin value="-49"/>
     <yMin value="-362"/>
     <xMax value="1393"/>
@@ -20620,18 +20620,14 @@
       <color index="1" value="#55A5FEFF"/>
     </palette>
     <palette index="5">
-      <color index="0" value="#0B5BA8FF"/>
-      <color index="1" value="#55A5FEFF"/>
-    </palette>
-    <palette index="6">
       <color index="0" value="#EFBB43FF"/>
       <color index="1" value="#EAE2B1FF"/>
     </palette>
-    <palette index="7">
+    <palette index="6">
       <color index="0" value="#FFDA99FF"/>
       <color index="1" value="#FF5140FF"/>
     </palette>
-    <palette index="8">
+    <palette index="7">
       <color index="0" value="#FFE10BFF"/>
       <color index="1" value="#FF0035FF"/>
     </palette>

According to Wakamai Fondue, the CPAL palettes currently inside Bungee Color COLRv0 font are these:

No idea where FireFox got those grey colors from..

[djrrb]

Hi Cosimo, thanks so much for finding and correcting this duplicate! Funny to see Firefox’s reaction to it.

Truly appreciate you taking the time to identify and correct this issue!