fix(webgl): use stable numeric sort for merging texture pages

The merging-pages index sort used (a, b) => a > b ? 1 : -1, which
returns -1 when a === b and violates the comparator contract. Use
(a, b) => a - b for ascending numeric order.

Co-authored-by: Cursor <cursoragent@cursor.com>

addons/addon-webgl/src/TextureAtlas.ts

@@ -191,7 +191,7 @@ export class TextureAtlas implements ITextureAtlas {
         return newPage;
       }
 
-      const sortedMergingPagesIndexes = mergingPages.map(e => e.glyphs[0].texturePage).sort((a, b) => a > b ? 1 : -1);
+      const sortedMergingPagesIndexes = mergingPages.map(e => e.glyphs[0].texturePage).sort((a, b) => a - b);
       const mergedPageIndex = this.pages.length - mergingPages.length;
 
       // Merge into the new page