Editorial: Don't use SameValue in DetachArrayBuffer (#2745)

SameValue accepts only ECMAScript language values as args,
so DetachArrayBuffer's use of SameValue asserts that
detach keys are ECMAScript language values.
But detach keys should be as opaque as possible,
so replace `SameValue` with `is`.

spec.html

@@ -40848,7 +40848,7 @@ <h1>
         <emu-alg>
           1. Assert: IsSharedArrayBuffer(_arrayBuffer_) is *false*.
           1. If _key_ is not present, set _key_ to *undefined*.
-          1. If SameValue(_arrayBuffer_.[[ArrayBufferDetachKey]], _key_) is *false*, throw a *TypeError* exception.
+          1. If _arrayBuffer_.[[ArrayBufferDetachKey]] is not _key_, throw a *TypeError* exception.
           1. Set _arrayBuffer_.[[ArrayBufferData]] to *null*.
           1. Set _arrayBuffer_.[[ArrayBufferByteLength]] to 0.
           1. Return ~unused~.