Fallback to an exhaustive search, in corrupt PDF files, for NameTrees/NumberTrees that are not correctly ordered (issue 10272)

According to the specification, see https://www.adobe.com/content/dam/acom/en/devnet/acrobat/pdfs/PDF32000_2008.pdf#G6.2384179, the keys of NameTree/NumberTree should be ordered.
For corrupt PDF files, which violate this assumption, we thus need to fallback to an exhaustive search in order to e.g. find all destinations.

*Please note:* Given that this only implements a fallback for the "final" node of the Tree, there's obviously a risk that the patch isn't sufficient for dealing with all kinds of out-of-order corruption. However, this kind of problem should be rare in practice, and without a real-world test-case it's difficult to implement a completely general solution (and there's obviously a question if you'd even want to).

src/core/obj.js

@@ -1648,7 +1648,7 @@ class NameOrNumberTree {
     // contains the key we are looking for.
     while (kidsOrEntries.has('Kids')) {
       if (++loopCount > MAX_LEVELS) {
-        warn('Search depth limit reached for "' + this._type + '" tree.');
+        warn(`Search depth limit reached for "${this._type}" tree.`);
         return null;
       }
 
@@ -1696,6 +1696,19 @@ class NameOrNumberTree {
           return xref.fetchIfRef(entries[m + 1]);
         }
       }
+
+      // Fallback to an exhaustive search, in an attempt to handle corrupt
+      // PDF files where keys are not correctly ordered (fixes issue 10272).
+      info(`Falling back to an exhaustive search, for key "${key}", ` +
+           `in "${this._type}" tree.`);
+      for (let m = 0, mm = entries.length; m < mm; m += 2) {
+        const currentKey = xref.fetchIfRef(entries[m]);
+        if (currentKey === key) {
+          warn(`The "${key}" key was found at an incorrect, ` +
+               `i.e. out-of-order, position in "${this._type}" tree.`);
+          return xref.fetchIfRef(entries[m + 1]);
+        }
+      }
     }
     return null;
   }