Reference newly landed WebIDL "transferable" definition (#732)

As promised, the local algorithm "detachable" migrated to WebIDL[1],
so we can drop our copy of the algorithm and reference WebIDL's
version instead, which is identical except for a name change[3].

(If you're building the spec locally and run into errors, force
a Bikeshed update[2] to ensure you have the latest indexes.)

1: whatwg/webidl@d6927d5
2: https://speced.github.io/bikeshed/#updating-bikeshed
3: whatwg/webidl#1419 (comment)

Ref: #351

index.bs

@@ -937,29 +937,12 @@ When the {{MLContext/[[contextType]]}} is set to [=context type/default=] with t
 
 ### {{MLNamedArrayBufferViews}} transfer algorithm ### {#mlnamedarraybufferviews-transfer-alg}
 
-<details open algorithm>
-  <summary>
-    A [=buffer source type=] instance |bufferSource| is
-    <dfn for="BufferSource">detachable</dfn> if the following steps return true:
-  </summary>
-    1.  Let |jsArrayBuffer| be the result of [=converted to a JavaScript value|converting=]
-        |bufferSource| to a JavaScript value.
-    1.  If |jsArrayBuffer| has a \[[ViewedArrayBuffer]] internal slot, then set |jsArrayBuffer| to
-        |jsArrayBuffer|.\[[ViewedArrayBuffer]].
-    1.  If [$IsSharedArrayBuffer$](|jsArrayBuffer|) is true, then return false.
-    1.  If [$IsDetachedBuffer$](|jsArrayBuffer|) is true, return false.
-    1.  If |jsArrayBuffer|.\[[ArrayBufferDetachKey]] is not undefined, return false.
-    1.  Return true.
-</details>
-
-Issue(351): Move the above algorithm into [[WEBIDL]].
-
 <details open algorithm>
   <summary>
     To <dfn for="MLNamedArrayBufferViews">transfer</dfn> an {{MLNamedArrayBufferViews}} |views| with [=realm=] |realm|:
   </summary>
     1. [=map/For each=] |name| → |view| of |views|:
-        1. If |view| is not [=BufferSource/detachable=], then throw a {{TypeError}}.
+        1. If |view| is not [=BufferSource/transferable=], then throw a {{TypeError}}.
     1. Let |transferredViews| be a new {{MLNamedArrayBufferViews}}.
     1. [=map/For each=] |name| → |view| of |views|:
         1. Let |transferredBuffer| be the result of [=ArrayBuffer/transfer|transferring=] |view|'s [=BufferSource/underlying buffer=].