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;
       }