Fix webgl rendering corruption from atlas page merges

addons/addon-webgl/src/GlyphRenderer.ts

@@ -358,7 +358,9 @@ export class GlyphRenderer extends Disposable {
     gl.bindBuffer(gl.ARRAY_BUFFER, this._attributesBuffer);
     gl.bufferData(gl.ARRAY_BUFFER, activeBuffer.subarray(0, bufferLength), gl.STREAM_DRAW);
 
-    // Bind the atlas page texture if they have changed
+    // Bind the atlas page texture if they have changed. AtlasPage.version is globally
+    // monotonic, so a page object swap at the same index (which happens after a page merge)
+    // is detected by the same comparison.
     for (let i = 0; i < this._atlas.pages.length; i++) {
       if (this._atlas.pages[i].version !== this._atlasTextures[i].version) {
         this._bindAtlasPageTexture(gl, this._atlas, i);