[NativeFS] Remove legacy camelCase enum values.

The ChooseFileSystemEntriesType enum values were changed from camel-case
to dashDelimited in M81. In M82 we only want the new dash-delimeted
version available, so remove the legacy ones.

Bug: 1020715
Change-Id: Id36e8d1009a53039404859c26c8508a5843c7624
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2095138
Commit-Queue: Marijn Kruisselbrink <mek@chromium.org>
Commit-Queue: Olivier Yiptong <oyiptong@chromium.org>
Auto-Submit: Marijn Kruisselbrink <mek@chromium.org>
Reviewed-by: Olivier Yiptong <oyiptong@chromium.org>
Cr-Commit-Position: refs/heads/master@{#748352}

third_party/blink/renderer/modules/native_file_system/choose_file_system_entries_options.idl

@@ -5,11 +5,8 @@
 // https://wicg.github.io/native-file-system/#enumdef-choosefilesystementriestype
 enum ChooseFileSystemEntriesType {
     "open-file",
-    "openFile",
     "save-file",
-    "saveFile",
     "open-directory",
-    "openDirectory"
 };
 
 // https://wicg.github.io/native-file-system/#dictdef-choosefilesystementriesoptions