Make Date serialization follow Date Time String format (#237)

Author: lutien

index.bs

@@ -94,7 +94,7 @@ spec: ECMASCRIPT; urlPrefix: https://tc39.es/ecma262/
     text: CreateSetIterator; url: sec-createsetiterator
     text: Date; url: sec-date-constructor
     text: Date Time String Format; url: sec-date-time-string-format
-    text: Date.ToDateString; url: sec-todatestring
+    text: Date.toISOString; url: sec-date.prototype.toisostring
     text: EnumerableOwnPropertyNames; url: sec-enumerableownpropertynames
     text: Get; url: sec-get
     text: HasProperty; url: sec-hasproperty
@@ -114,7 +114,6 @@ spec: ECMASCRIPT; urlPrefix: https://tc39.es/ecma262/
     text: StringToBigInt; url: sec-stringtobigint
     text: StringToNumber; url: sec-stringtonumber
     text: RegExp; url: sec-regexp-pattern-flags
-    text: ThisTimeValue; url: thistimevalue
     text: ToString; url: sec-tostring
     text: Type; url: sec-ecmascript-data-types-and-values
     text: abrupt completion; url: sec-completion-record-specification-type
@@ -125,6 +124,7 @@ spec: ECMASCRIPT; urlPrefix: https://tc39.es/ecma262/
     text: realm; url: sec-code-realms
     text: running execution context; url: running-execution-context
     text: time value; url: sec-time-values-and-time-range
+    text: throw completion; url: sec-completion-record-specification-type
 spec: GEOMETRY; urlPrefix: https://drafts.fxtf.org/geometry/
   type: dfn
     text: rectangle; url: rectangle
@@ -1749,7 +1749,9 @@ an |ownership type|, a |serialization internal map| and a |realm|:
 
     <dt>|value| has a \[[DateValue]] [=internal slot=].
     <dd>
-      1. Let |serialized| be [=Date.ToDateString=]([=thisTimeValue=](|value|)).
+      1. Set |serialized| to [=Call=]([=Date.toISOString=], |value|).
+
+      1. Assert: |serialized| is not a [=throw completion=].
 
       1. Let |remote value| be a map matching the <code>DateRemoteValue</code>
          production in the [=local end definition=], with the <code>handle</code>