Rename [Unforgeable] to [LegacyUnforgeable]

Part of #350.

index.bs

@@ -1971,7 +1971,7 @@ are applicable only to regular attributes:
 [{{LegacyLenientThis}}],
 [{{PutForwards}}],
 [{{Replaceable}}],
-[{{Unforgeable}}].
+[{{LegacyUnforgeable}}].
 
 <pre class="grammar" id="prod-ReadOnlyMember">
     ReadOnlyMember :
@@ -2414,7 +2414,7 @@ The following extended attributes are applicable to operations:
 [{{Exposed}}],
 [{{NewObject}}],
 [{{SecureContext}}],
-[{{Unforgeable}}].
+[{{LegacyUnforgeable}}].
 
 <pre class="grammar" id="prod-DefaultValue">
     DefaultValue :
@@ -10781,9 +10781,9 @@ See [[#es-DOMString]] for the specific requirements that the use of [{{TreatNull
 </div>
 
 
-<h4 id="Unforgeable" extended-attribute lt="Unforgeable">[Unforgeable]</h4>
+<h4 id="LegacyUnforgeable" extended-attribute lt="LegacyUnforgeable" oldids="Unforgeable">[LegacyUnforgeable]</h4>
 
-If the [{{Unforgeable}}] [=extended attribute=] appears on
+If the [{{LegacyUnforgeable}}] [=extended attribute=] appears on
 [=regular attributes=] or non-[=static operations|static=] [=operations=],
 it indicates that the attribute or operation
 will be reflected as an ECMAScript property
@@ -10797,18 +10797,18 @@ rather than on its prototype.
 An attribute or operation is said to be
 <dfn id="dfn-unforgeable-on-an-interface" export>unforgeable</dfn> on a given interface |A|
 if the attribute or operation is declared on |A|,
-and is annotated with the [{{Unforgeable}}] [=extended attribute=].
+and is annotated with the [{{LegacyUnforgeable}}] [=extended attribute=].
 
-The [{{Unforgeable}}] extended attribute must [=takes no arguments|take no arguments=].
+The [{{LegacyUnforgeable}}] extended attribute must [=takes no arguments|take no arguments=].
 
-The [{{Unforgeable}}] [=extended attribute=] must not appear
+The [{{LegacyUnforgeable}}] [=extended attribute=] must not appear
 on anything other than a [=regular attribute=]
 or a non-[=static operations|static=] [=operation=].
 If it does appear on an [=operation=],
 then it must appear on all operations
 with the same [=identifier=] on that interface.
 
-The [{{Unforgeable}}] extended attribute must not be used
+The [{{LegacyUnforgeable}}] extended attribute must not be used
 on an attribute declared on a [=namespace=].
 
 If an attribute or operation |X| is [=unforgeable=] on an interface |A|,
@@ -10824,7 +10824,7 @@ with the same [=identifier=] as |X|.
     <pre highlight="webidl">
         [Exposed=Window]
         interface A1 {
-          [Unforgeable] readonly attribute DOMString x;
+          [LegacyUnforgeable] readonly attribute DOMString x;
         };
         [Exposed=Window]
         interface B1 : A1 {
@@ -10846,18 +10846,18 @@ See [[#es-attributes]],
 [[#es-legacy-platform-objects]] and
 [[#legacy-platform-object-defineownproperty]]
 for the specific requirements that the use of
-[{{Unforgeable}}] entails.
+[{{LegacyUnforgeable}}] entails.
 
 <div class="example">
 
     The following [=IDL fragment=] defines
     an interface that has two [=attributes=],
-    one of which is designated as [{{Unforgeable}}]:
+    one of which is designated as [{{LegacyUnforgeable}}]:
 
     <pre highlight="webidl">
         [Exposed=Window]
         interface System {
-          [Unforgeable] readonly attribute DOMString username;
+          [LegacyUnforgeable] readonly attribute DOMString username;
           readonly attribute long long loginTime;
         };
     </pre>