Replace `/` division with multiplication and custom `divide()` function (#34245)

* Convert bulk of division to multiplication

* Use custom divide() function instead of Dart Sass math module for greater compatibility

* Apply suggestions from code review

* Fix functions

1 files changed, 28 insertions, 3 deletions

diff --git a/scss/_functions.scss b/scss/_functions.scss
index f92355f42..2d3478bfa 100644
--- a/scss/_functions.scss
+++ b/scss/_functions.scss
@@ -95,7 +95,7 @@
 // Color contrast
 // See https://github.com/twbs/bootstrap/pull/30168
 
-// A list of pre-calculated numbers of pow(($value / 255 + .055) / 1.055, 2.4). (from 0 to 255)
+// A list of pre-calculated numbers of pow(divide((divide($value, 255) + .055), 1.055), 2.4). (from 0 to 255)
 // stylelint-disable-next-line scss/dollar-variable-default, scss/dollar-variable-pattern
 $_luminance-list: .0008 .001 .0011 .0013 .0015 .0017 .002 .0022 .0025 .0027 .003 .0033 .0037 .004 .0044 .0048 .0052 .0056 .006 .0065 .007 .0075 .008 .0086 .0091 .0097 .0103 .011 .0116 .0123 .013 .0137 .0144 .0152 .016 .0168 .0176 .0185 .0194 .0203 .0212 .0222 .0232 .0242 .0252 .0262 .0273 .0284 .0296 .0307 .0319 .0331 .0343 .0356 .0369 .0382 .0395 .0409 .0423 .0437 .0452 .0467 .0482 .0497 .0513 .0529 .0545 .0561 .0578 .0595 .0612 .063 .0648 .0666 .0685 .0704 .0723 .0742 .0762 .0782 .0802 .0823 .0844 .0865 .0887 .0908 .0931 .0953 .0976 .0999 .1022 .1046 .107 .1095 .1119 .1144 .117 .1195 .1221 .1248 .1274 .1301 .1329 .1356 .1384 .1413 .1441 .147 .15 .1529 .1559 .159 .162 .1651 .1683 .1714 .1746 .1779 .1812 .1845 .1878 .1912 .1946 .1981 .2016 .2051 .2086 .2122 .2159 .2195 .2232 .227 .2307 .2346 .2384 .2423 .2462 .2502 .2542 .2582 .2623 .2664 .2705 .2747 .2789 .2831 .2874 .2918 .2961 .3005 .305 .3095 .314 .3185 .3231 .3278 .3325 .3372 .3419 .3467 .3515 .3564 .3613 .3663 .3712 .3763 .3813 .3864 .3916 .3968 .402 .4072 .4125 .4179 .4233 .4287 .4342 .4397 .4452 .4508 .4564 .4621 .4678 .4735 .4793 .4851 .491 .4969 .5029 .5089 .5149 .521 .5271 .5333 .5395 .5457 .552 .5583 .5647 .5711 .5776 .5841 .5906 .5972 .6038 .6105 .6172 .624 .6308 .6376 .6445 .6514 .6584 .6654 .6724 .6795 .6867 .6939 .7011 .7084 .7157 .7231 .7305 .7379 .7454 .7529 .7605 .7682 .7758 .7835 .7913 .7991 .807 .8148 .8228 .8308 .8388 .8469 .855 .8632 .8714 .8796 .8879 .8963 .9047 .9131 .9216 .9301 .9387 .9473 .956 .9647 .9734 .9823 .9911 1;
 
@@ -123,7 +123,7 @@ $_luminance-list: .0008 .001 .0011 .0013 .0015 .0017 .002 .0022 .0025 .0027 .003
   $l1: luminance($background);
   $l2: luminance(opaque($background, $foreground));
 
-  @return if($l1 > $l2, ($l1 + .05) / ($l2 + .05), ($l2 + .05) / ($l1 + .05));
+  @return if($l1 > $l2, divide($l1 + .05, $l2 + .05), divide($l2 + .05, $l1 + .05));
 }
 
 // Return WCAG2.0 relative luminance
@@ -137,7 +137,7 @@ $_luminance-list: .0008 .001 .0011 .0013 .0015 .0017 .002 .0022 .0025 .0027 .003
   );
 
   @each $name, $value in $rgb {
-    $value: if($value / 255 < .03928, $value / 255 / 12.92, nth($_luminance-list, $value + 1));
+    $value: if(divide($value, 255) < .03928, divide(divide($value, 255), 12.92), nth($_luminance-list, $value + 1));
     $rgb: map-merge($rgb, ($name: $value));
   }
 
@@ -219,3 +219,28 @@ $_luminance-list: .0008 .001 .0011 .0013 .0015 .0017 .002 .0022 .0025 .0027 .003
 
   @return if($return-calc == true, calc(#{$value1} - #{$value2}), $value1 + unquote(" - ") + $value2);
 }
+
+@function divide($dividend, $divisor, $precision: 10) {
+  $sign: if($dividend > 0 and $divisor > 0, 1, -1);
+  $dividend: abs($dividend);
+  $divisor: abs($divisor);
+  $quotient: 0;
+  $remainder: $dividend;
+  @if $dividend == 0 {
+    @return 0;
+  }
+  @if $divisor == 0 {
+    @error "Cannot divide by 0";
+  }
+  @if $divisor == 1 {
+    @return $dividend;
+  }
+  @while $remainder >= $divisor {
+    $quotient: $quotient + 1;
+    $remainder: $remainder - $divisor;
+  }
+  @if $remainder > 0 and $precision > 0 {
+    $remainder: divide($remainder * 10, $divisor, $precision - 1) * .1;
+  }
+  @return ($quotient + $remainder) * $sign;
+}