Fix decodeAudioData algorithm logic

Per WG resolution 2025-05-15:
- Step 3 condition now correctly says "is not detached" instead of
  "is detached"
- Step 3.2 now correctly jumps to step 4.1 (error handling) if the
  ArrayBuffer detach operation throws

Also fixed "this operations" -> "this operation" typo.

This fixes #2637 and fixes #2646.

Author: padenot

index.bs

@@ -1237,14 +1237,14 @@ Methods</h4>
 
             2. Let <var>promise</var> be a new Promise.
 
-            3. If {{BaseAudioContext/decodeAudioData(audioData, successCallback, errorCallback)/audioData!!argument}} 
-                is [=BufferSource/detached=], execute the following steps:
+            3. If {{BaseAudioContext/decodeAudioData(audioData, successCallback, errorCallback)/audioData!!argument}}
+                is not [=BufferSource/detached=], execute the following steps:
 
                 1. Append <var>promise</var> to {{BaseAudioContext/[[pending promises]]}}.
 
                 2. [=ArrayBuffer/Detach=]
                     the {{BaseAudioContext/decodeAudioData(audioData, successCallback, errorCallback)/audioData!!argument}} {{ArrayBuffer}}.
-                    If this operations throws, jump to the step 3. 
+                    If this operation throws, jump to step 4.1. 
 
                 3. Queue a decoding operation to be performed on another thread.