Merge pull request #20716 from Snuffleupagus/src-display-getOrInsert

Use `Map.prototype.getOrInsert()` more in the `src/display/` folder

Author: Snuffleupagus

src/display/annotation_layer.js

@@ -3877,12 +3877,7 @@ class AnnotationLayer {
         this.#elements.push(element);
 
         if (data.popupRef) {
-          const elements = popupToElements.get(data.popupRef);
-          if (!elements) {
-            popupToElements.set(data.popupRef, [element]);
-          } else {
-            elements.push(element);
-          }
+          popupToElements.getOrInsert(data.popupRef, []).push(element);
         }
       }
 

src/display/canvas.js

@@ -989,11 +989,10 @@ class CanvasGraphics {
           : [currentTransform.slice(0, 4), fillColor]
       );
 
-      cache = this._cachedBitmapsMap.get(mainKey);
-      if (!cache) {
-        cache = new Map();
-        this._cachedBitmapsMap.set(mainKey, cache);
-      }
+      cache = this._cachedBitmapsMap.getOrInsertComputed(
+        mainKey,
+        () => new Map()
+      );
       const cachedImage = cache.get(cacheKey);
       if (cachedImage && !isPatternFill) {
         const offsetX = Math.round(