Limit the Math.sumPrecise polyfill to non-MOZCENTRAL builds

After https://bugzilla.mozilla.org/show_bug.cgi?id=1985121 this functionality is now guaranteed to be available in Firefox.
Unfortunately general browser support is still somewhat lacking; see https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Math/sumPrecise#browser_compatibility

Also, while unrelated, use the `MathClamp` helper in the `applyOpacity` function.

Author: Snuffleupagus

src/display/display_utils.js

@@ -799,7 +799,7 @@ class CSSConstants {
 }
 
 function applyOpacity(r, g, b, opacity) {
-  opacity = Math.min(Math.max(opacity ?? 1, 0), 1);
+  opacity = MathClamp(opacity ?? 1, 0, 1);
   const white = 255 * (1 - opacity);
   r = Math.round(r * opacity + white);
   g = Math.round(g * opacity + white);

src/shared/util.js

@@ -1235,9 +1235,12 @@ function MathClamp(v, min, max) {
   return Math.min(Math.max(v, min), max);
 }
 
-// TODO: Remove this once the `javascript.options.experimental.math_sumprecise`
-//       preference is removed from Firefox.
-if (typeof Math.sumPrecise !== "function") {
+// TODO: Remove this once `Math.sumPrecise` is generally available.
+if (
+  (typeof PDFJSDev === "undefined" ||
+    PDFJSDev.test("SKIP_BABEL && !MOZCENTRAL")) &&
+  typeof Math.sumPrecise !== "function"
+) {
   // Note that this isn't a "proper" polyfill, but since we're only using it to
   // replace `Array.prototype.reduce()` invocations it should be fine.
   Math.sumPrecise = function (numbers) {