Specify identifier references denoting extension members

specification/dartLangSpec.tex

@@ -41,6 +41,7 @@
 %   'class' scope.
 % - Add specification of `>>` in JavaScript compiled code, in appendix.
 % - Integrate the specification of extension methods into this document.
+% - Specify identifier references denoting extension members.
 %
 % 2.7
 % - Rename non-terminals `<...Definition>` to `<...Declaration>` (e.g., it is
@@ -16244,10 +16245,19 @@ \subsection{Identifier Reference}
   where $T$ is a subtype of any other type $S$
   such that $v$ is known to have type $S$,
   in which case the static type of $e$ is $T$.
+\item
+  % Extension getter invocation by scope.
+  If $D$ is a declaration of an instance getter in an extension $E$
+  then the static type of $e$ is the return type of $D$.
+\item
+  % Extension method tear-off by scope.
+  If $D$ is a declaration of an instance method
+  in an extension $E$ then the static type of $e$ is
+  the function type of $D$.
 \item
   \commentary{%
     A lexical lookup will never yield a declaration $D$
-    which is an instance member.%
+    which is an instance member of a class.%
   }
 \end{itemize}
 \vspace{-1ex}
@@ -16334,6 +16344,17 @@ \subsection{Identifier Reference}
   then $e$ evaluates to the function object obtained by closurization
   (\ref{functionClosurization})
   of $D$.
+\item
+  If $D$ is an instance getter declaration in an extension $E$,
+  then $e$ evaluates to the result of invoking said getter
+  with the current binding of \THIS{}, and
+  the current bindings of the type parameters declared by $D$.
+\item
+  If $D$ is an instance method declaration in an extension $E$
+  with type parameters \List{X}{1}{s},
+  then $e$ evaluates to the result of the extension method closurization
+  \code{$E$<\List{X}{1}{s}>(\THIS).\id}
+  (\ref{extensionMethodClosurization}).
 \item
   If $D$ is a local variable $v$
   (\commentary{which can be a formal parameter})