refactor: remove unused m2 utils (#31338)

Author: andrewseguin

src/material/core/tokens/_m2-utils.scss

@@ -1,11 +1,5 @@
-@use 'sass:color';
-@use 'sass:math';
-@use 'sass:meta';
 @use 'sass:map';
 
-// Indicates whether we're building internally. Used for backwards compatibility.
-$private-is-internal-build: false;
-
 // Gets the theme's system values as a flat map.
 @function get-system($theme) {
   $system: map.get($theme, _mat-system);
@@ -15,63 +9,3 @@ $private-is-internal-build: false;
 
   @return ();
 }
-
-/// Inherited function from MDC that computes which contrast tone to use on top of a color.
-/// This is used only in a narrow set of use cases when generating M2 button tokens to maintain
-/// backwards compatibility.
-/// @param {Color} $value Color for which we're calculating the contrast tone.
-/// @param {Boolean} $is-dark Whether the current theme is dark.
-/// @return {Map} Either `dark` or `light`.
-@function contrast-tone($value, $is-dark) {
-  @if ($value == 'dark') {
-    @return 'light';
-  }
-
-  @if ($value == 'light') {
-    @return 'dark';
-  }
-
-  // Fallback if the app is using a non-color palette (e.g. CSS variable based).
-  @if (meta.type-of($value) != 'color') {
-    @return if($is-dark, 'light', 'dark');
-  }
-
-  $minimum-contrast: 3.1;
-  $light-contrast: _contrast($value, #fff);
-  $dark-contrast: _contrast($value, rgba(0, 0, 0, 0.87));
-
-  @if ($light-contrast < $minimum-contrast) and ($dark-contrast > $light-contrast) {
-    @return 'dark';
-  }
-
-  @return 'light';
-}
-
-@function _linear-channel-value($channel-value) {
-  $normalized-channel-value: math.div($channel-value, 255);
-
-  @if ($normalized-channel-value < 0.03928) {
-    @return math.div($normalized-channel-value, 12.92);
-  }
-
-  @return math.pow(math.div($normalized-channel-value + 0.055, 1.055), 2.4);
-}
-
-// Calculate the luminance for a color.
-// See https://www.w3.org/TR/WCAG20-TECHS/G17.html#G17-tests
-@function _luminance($color) {
-  $red: _linear-channel-value(color.red($color));
-  $green: _linear-channel-value(color.green($color));
-  $blue: _linear-channel-value(color.blue($color));
-
-  @return 0.2126 * $red + 0.7152 * $green + 0.0722 * $blue;
-}
-
-// Calculate the contrast ratio between two colors.
-// See https://www.w3.org/TR/WCAG20-TECHS/G17.html#G17-tests
-@function _contrast($back, $front) {
-  $back-lum: _luminance($back) + 0.05;
-  $fore-lum: _luminance($front) + 0.05;
-
-  @return math.div(math.max($back-lum, $fore-lum), math.min($back-lum, $fore-lum));
-}