Fix crash with relative colors in @font-palette-values

Simply skip such override-colors for now and leave a TODO on how to fix
it properly.

Bug: 417172068
Change-Id: I8bff5a2758b23fda57f73429d4b64d843055e80e
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/6532438
Commit-Queue: Rune Lillesveen 
Reviewed-by: Dominik Röttsches 
Cr-Commit-Position: refs/heads/main@{#1459324}

Author: lilles

css/css-fonts/font-palette-relative-color-crash.html

@@ -0,0 +1,18 @@
+>
+<title>CSS Fonts: override-colors with relative color crashing Chrometitle>
+<link rel="help" href="https://crbug.com/417172068">
+<style>
+  @font-face {
+    font-family: Foo;
+    src: url(notfound.ttf);
+  }
+  @font-palette-values --foo {
+    font-family: Foo;
+    override-colors: 0 lch(from blue calc(0.5 * l) c h);
+  }
+  #target {
+    font-family: Foo;
+    font-palette: --foo;
+  }
+style>
+<div id="target">Foodiv>