Add steps to deserialize script.ReadableStreamRemoteValue.

Author: lutien

index.bs

@@ -11712,6 +11712,13 @@ To <dfn>deserialize local value</dfn> given |local protocol value|, |realm| and
 1. If |local protocol value| matches the <code>script.ChannelValue</code> production,
    return [=create a channel=] with |session|, |realm| and |local protocol value|.
 
+1. If |local protocol value| matches the <code>script.ReadableStreamRemoteValue</code> production, then:
+
+   1. Let |stream settings| be the result of [=trying=] to [=get readable stream settings=] with
+     |session| and |local protocol value|["<code>stream</code>"].
+
+   1. Return |stream settings|[[=stream settings/stream=]].
+
 1. Let |type| be the value of the <code>type</code> field of |local protocol value| or undefined if
    no such a field.