fix: Fix detection of flac support on Safari (#6250)

When constructing the MediaDecodingConfigurations to query media capabilities in `stream_utils.js`, the spelling of "fLaC" should not change to "flac" on Safari. This is because on Safari the query will return `supported: false` for "flac" but `supported: true` for "fLaC".

This change allows manifests with "fLaC" codecs to work properly on Safari when using MSE / Managed Media Source.

Fixes #6249

AUTHORS

@@ -54,6 +54,7 @@ Jonas Birmé <[email protected]>
 Jozef Chúťka <[email protected]>
 Jun Hong Chong <[email protected]>
 Jürgen Kartnaller <[email protected]>
+Justin Swaney <[email protected]>
 JW Player <*@jwplayer.com>
 Konstantin Grushetsky <[email protected]>
 Lucas Gabriel Sánchez <[email protected]>

CONTRIBUTORS

@@ -82,6 +82,7 @@ Jozef Chúťka <[email protected]>
 Julian Domingo <[email protected]>
 Jun Hong Chong <[email protected]>
 Jürgen Kartnaller <[email protected]>
+Justin Swaney <[email protected]>
 Konstantin Grushetsky <[email protected]>
 Leandro Ribeiro Moreira <[email protected]>
 Loïc Raux <[email protected]>

lib/util/stream_utils.js

@@ -839,7 +839,7 @@ shaka.util.StreamUtils = class {
     // currently don't support 'fLaC', while 'flac' is supported by most
     // major browsers.
     // See https://bugs.chromium.org/p/chromium/issues/detail?id=1422728
-    if (codecs === 'fLaC') {
+    if (codecs === 'fLaC' && !shaka.util.Platform.isSafari()) {
       return 'flac';
     }