Use more for...of loops in the code-base

Note that these cases, which are all in older code, were found using the [`unicorn/no-for-loop`](https://github.com/sindresorhus/eslint-plugin-unicorn/blob/main/docs/rules/no-for-loop.md) ESLint plugin rule.
However, note that I've opted not to enable this rule by default since there's still *some* cases where I do think that it makes sense to allow "regular" for-loops.

src/core/cff_parser.js

@@ -1682,9 +1682,7 @@ class CFFCompiler {
   compileDict(dict, offsetTracker) {
     const out = [];
     // The dictionary keys must be in a certain order.
-    const order = dict.order;
-    for (let i = 0; i < order.length; ++i) {
-      const key = order[i];
+    for (const key of dict.order) {
       if (!(key in dict.values)) {
         continue;
       }

src/core/type1_font.js

@@ -219,9 +219,8 @@ class Type1Font {
 
   getCharset() {
     const charset = [".notdef"];
-    const charstrings = this.charstrings;
-    for (let glyphId = 0; glyphId < charstrings.length; glyphId++) {
-      charset.push(charstrings[glyphId].glyphName);
+    for (const { glyphName } of this.charstrings) {
+      charset.push(glyphName);
     }
     return charset;
   }

src/core/type1_parser.js

@@ -576,7 +576,7 @@ const Type1Parser = (function Type1ParserClosure() {
           privateData,
         },
       };
-      let token, length, data, lenIV, encoded;
+      let token, length, data, lenIV;
       while ((token = this.getToken()) !== null) {
         if (token !== "/") {
           continue;
@@ -604,7 +604,7 @@ const Type1Parser = (function Type1ParserClosure() {
               this.getToken(); // read in 'RD' or '-|'
               data = length > 0 ? stream.getBytes(length) : new Uint8Array(0);
               lenIV = program.properties.privateData.lenIV;
-              encoded = this.readCharStrings(data, lenIV);
+              const encoded = this.readCharStrings(data, lenIV);
               this.nextChar();
               token = this.getToken(); // read in 'ND' or '|-'
               if (token === "noaccess") {
@@ -629,7 +629,7 @@ const Type1Parser = (function Type1ParserClosure() {
               this.getToken(); // read in 'RD' or '-|'
               data = length > 0 ? stream.getBytes(length) : new Uint8Array(0);
               lenIV = program.properties.privateData.lenIV;
-              encoded = this.readCharStrings(data, lenIV);
+              const encoded = this.readCharStrings(data, lenIV);
               this.nextChar();
               token = this.getToken(); // read in 'NP' or '|'
               if (token === "noaccess") {
@@ -675,9 +675,7 @@ const Type1Parser = (function Type1ParserClosure() {
         }
       }
 
-      for (let i = 0; i < charstrings.length; i++) {
-        const glyph = charstrings[i].glyph;
-        encoded = charstrings[i].encoded;
+      for (const { encoded, glyph } of charstrings) {
         const charString = new Type1CharString();
         const error = charString.convert(
           encoded,

src/core/worker.js

@@ -263,8 +263,8 @@ class WorkerMessageHandler {
           // There may be a chance that `newPdfManager` is not initialized for
           // the first few runs of `readchunk` block of code. Be sure to send
           // all cached chunks, if any, to chunked_stream via pdf_manager.
-          for (let i = 0; i < cachedChunks.length; i++) {
-            newPdfManager.sendProgressiveData(cachedChunks[i]);
+          for (const chunk of cachedChunks) {
+            newPdfManager.sendProgressiveData(chunk);
           }
 
           cachedChunks = [];

src/display/canvas.js

@@ -2211,8 +2211,7 @@ class CanvasGraphics {
 
     ctx.save();
     ctx.beginPath();
-    for (let i = 0; i < paths.length; i++) {
-      const path = paths[i];
+    for (const path of paths) {
       ctx.setTransform.apply(ctx, path.transform);
       ctx.translate(path.x, path.y);
       path.addToPath(ctx, path.fontSize);