Add general iteration support in the RefSet and RefSetCache classes

This patch removes the existing `forEach` methods, in favor of making the classes properly iterable instead. Given that the classes are using a `Set` respectively a `Map` internally, implementing this is very easy/efficient and allows us to simplify some existing code.

src/core/catalog.js

@@ -1040,42 +1040,32 @@ class Catalog {
     return shadow(this, "jsActions", actions);
   }
 
-  fontFallback(id, handler) {
-    const promises = [];
-    this.fontCache.forEach(function (promise) {
-      promises.push(promise);
-    });
+  async fontFallback(id, handler) {
+    const translatedFonts = await Promise.all(this.fontCache);
 
-    return Promise.all(promises).then(translatedFonts => {
-      for (const translatedFont of translatedFonts) {
-        if (translatedFont.loadedName === id) {
-          translatedFont.fallback(handler);
-          return;
-        }
+    for (const translatedFont of translatedFonts) {
+      if (translatedFont.loadedName === id) {
+        translatedFont.fallback(handler);
+        return;
       }
-    });
+    }
   }
 
-  cleanup(manuallyTriggered = false) {
+  async cleanup(manuallyTriggered = false) {
     clearGlobalCaches();
     this.globalImageCache.clear(/* onlyData = */ manuallyTriggered);
     this.pageKidsCountCache.clear();
     this.pageIndexCache.clear();
     this.nonBlendModesSet.clear();
 
-    const promises = [];
-    this.fontCache.forEach(function (promise) {
-      promises.push(promise);
-    });
+    const translatedFonts = await Promise.all(this.fontCache);
 
-    return Promise.all(promises).then(translatedFonts => {
-      for (const { dict } of translatedFonts) {
-        delete dict.cacheKey;
-      }
-      this.fontCache.clear();
-      this.builtInCMapCache.clear();
-      this.standardFontDataCache.clear();
-    });
+    for (const { dict } of translatedFonts) {
+      delete dict.cacheKey;
+    }
+    this.fontCache.clear();
+    this.builtInCMapCache.clear();
+    this.standardFontDataCache.clear();
   }
 
   async getPageDict(pageIndex) {

src/core/evaluator.js

@@ -352,9 +352,9 @@ class PartialEvaluator {
     // When no blend modes exist, there's no need re-fetch/re-parse any of the
     // processed `Ref`s again for subsequent pages. This helps reduce redundant
     // `XRef.fetch` calls for some documents (e.g. issue6961.pdf).
-    processed.forEach(ref => {
+    for (const ref of processed) {
       nonBlendModesSet.put(ref);
-    });
+    }
     return false;
   }
 

src/core/image_utils.js

@@ -179,9 +179,9 @@ class GlobalImageCache {
 
   get _byteSize() {
     let byteSize = 0;
-    this._imageCache.forEach(imageData => {
+    for (const imageData of this._imageCache) {
       byteSize += imageData.byteSize;
-    });
+    }
     return byteSize;
   }
 

src/core/primitives.js

@@ -350,10 +350,8 @@ class RefSet {
     this._set.delete(ref.toString());
   }
 
-  forEach(callback) {
-    for (const ref of this._set.values()) {
-      callback(ref);
-    }
+  [Symbol.iterator]() {
+    return this._set.values();
   }
 
   clear() {
@@ -386,10 +384,8 @@ class RefSetCache {
     this._map.set(ref.toString(), this.get(aliasRef));
   }
 
-  forEach(callback) {
-    for (const value of this._map.values()) {
-      callback(value);
-    }
+  [Symbol.iterator]() {
+    return this._map.values();
   }
 
   clear() {