add missing terminals to Other and ArgumentNameKeyword (#814)

Fixes #813

Author: bathos

index.bs

@@ -695,8 +695,10 @@ underscore.
         "interface"
         "iterable"
         "maplike"
+        "mixin"
         "namespace"
         "partial"
+        "readonly"
         "required"
         "setlike"
         "setter"
@@ -6905,6 +6907,7 @@ five forms are allowed.
         "FrozenArray"
         "Infinity"
         "NaN"
+        "Promise"
         "USVString"
         "any"
         "boolean"
@@ -6918,8 +6921,10 @@ five forms are allowed.
         "octet"
         "or"
         "optional"
+        "record"
         "sequence"
         "short"
+        "symbol"
         "true"
         "unsigned"
         "void"