Use ReadOnlyFile for hyphenation dictionary

Also fix a typo.

These are opened with FLAG_READ over here
https://source.chromium.org/chromium/chromium/src/+/master:content/browser/hyphenation/hyphenation_impl.cc;drc=da8e399b1f509d29565224190204860b22c9062b;l=51

Bug: 1130762
Change-Id: I6840ea5399ca7d7d75592865a02a491cff229199
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2462555Reviewed-by: Koji Ishii <kojii@chromium.org>
Commit-Queue: Alex Gough <ajgo@chromium.org>
Cr-Commit-Position: refs/heads/master@{#816242}

third_party/blink/public/mojom/hyphenation/hyphenation.mojom

@@ -4,12 +4,12 @@
 
 module blink.mojom;
 
-import "mojo/public/mojom/base/file.mojom";
+import "mojo/public/mojom/base/read_only_file.mojom";
 
 // Loads hyphenation dictionary.
 interface Hyphenation {
-  // Returns a handle to the raw hyphneation dictionary.
+  // Returns a handle to the raw hyphenation dictionary.
   [Sync]
   OpenDictionary(string locale) => (
-      mojo_base.mojom.File? hyphenation_dictionary_handle);
+      mojo_base.mojom.ReadOnlyFile? hyphenation_dictionary_handle);
 };