[futures.task.members] Use math mode for indices and non-C++ ellipses

Author: jwakely

source/threads.tex

@@ -5038,7 +5038,7 @@
 \begin{itemdescr}
 \pnum
 \requires
-\tcode{\placeholdernc{INVOKE}<R>(f, t1, t2, ..., tN)}, where \tcode{t1, t2, ..., tN} are values
+\tcode{\placeholdernc{INVOKE}<R>(f, t$_1$, t$_2$, $\dotsc$, t$_N$)}, where \tcode{t$_1$, t$_2$, $\dotsc$, t$_N$} are values
 of the corresponding types in \tcode{ArgTypes...}, shall be a valid expression. Invoking
 a copy of \tcode{f} shall behave the same as invoking \tcode{f}.
 
@@ -5160,10 +5160,10 @@
 
 \begin{itemdescr}
 \pnum
-\effects As if by \tcode{\placeholdernc{INVOKE}<R>(f, t1, t2, ..., tN)},
+\effects As if by \tcode{\placeholdernc{INVOKE}<R>(f, t$_1$, t$_2$, $\dotsc$, t$_N$)},
 where \tcode{f} is the
 stored task of \tcode{*this} and
-\tcode{t1, t2, ..., tN} are the values in \tcode{args...}. If the task returns normally,
+\tcode{t$_1$, t$_2$, $\dotsc$, t$_N$} are the values in \tcode{args...}. If the task returns normally,
 the return value is stored as the asynchronous result in the shared state of
 \tcode{*this}, otherwise the exception thrown by the task is stored. The
 shared state of \tcode{*this} is made ready, and any threads blocked in a
@@ -5190,9 +5190,9 @@
 
 \begin{itemdescr}
 \pnum
-\effects As if by \tcode{\placeholdernc{INVOKE}<R>(f, t1, t2, ..., tN)},
+\effects As if by \tcode{\placeholdernc{INVOKE}<R>(f, t$_1$, t$_2$, $\dotsc$, t$_N$)},
 where \tcode{f} is the stored task and
-\tcode{t1, t2, ..., tN} are the values in \tcode{args...}. If the task returns normally,
+\tcode{t$_1$, t$_2$, $\dotsc$, t$_N$} are the values in \tcode{args...}. If the task returns normally,
 the return value is stored as the asynchronous result in the shared state of
 \tcode{*this}, otherwise the exception thrown by the task is stored. In either
 case, this shall be done without making that state ready~(\ref{futures.state}) immediately. Schedules