Restrict the extended attributes for partial interfaces

It seems like a bad idea to allow [Global] on a partial interface.

The behavior of [Exposed] and [SecureContext] on partial interfaces is already
defined in the relevant algorithms.

The behavior of [OverrideBuiltins] is defined here with the same vague wording
used before. It might be better to disentangle the concept of an interface and
its syntactical structure.

Fixes #154.

index.bs

@@ -1037,28 +1037,6 @@ Note: A partial interface definition cannot specify that the interface
 Inheritance must be specified on the original [=interface=]
 definition.
 
-[=Extended attributes=] can be specified on
-[=partial interface=] definitions, with some
-limitations.  The following extended attributes must not
-be specified on partial interface definitions:
-[{{Constructor}}],
-[{{LegacyWindowAlias}}],
-[{{NamedConstructor}}],
-[{{NoInterfaceObject}}].
-
-Note: The above list of [=extended attributes=]
-is all of those defined in this document that are applicable to
-[=interfaces=] except for
-[{{Exposed}}],
-[{{Global}}],
-[{{OverrideBuiltins}}], and
-[{{SecureContext}}].
-
-Any [=extended attribute=] specified
-on a [=partial interface=] definition
-is considered to appear on the [=interface=]
-itself.
-
 The relevant language binding determines how interfaces correspond to constructs
 in the language.
 
@@ -1072,6 +1050,11 @@ The following extended attributes are applicable to interfaces:
 [{{OverrideBuiltins}}], and
 [{{SecureContext}}].
 
+The following extended attributes are applicable to [=partial interfaces=]:
+[{{Exposed}}],
+[{{OverrideBuiltins}}], and
+[{{SecureContext}}].
+
 Non-callback [=interfaces=] which are not annotated
 with a [{{NoInterfaceObject}}] [=extended attribute=],
 and [=callback interfaces=] which declare [=constants=]
@@ -9563,6 +9546,10 @@ definition, then that partial interface definition must
 be the part of the interface definition that defines
 the [=named property getter=].
 
+If the [{{OverrideBuiltins}}] extended attribute is specified on a
+[=partial interface=] definition, it is considered to appear on the
+[=interface=] itself.
+
 See [[#es-legacy-platform-objects]]
 and [[#legacy-platform-object-defineownproperty]]
 for the specific requirements that the use of