[LyX/master] Fix issue with CAS.

[Enrico Forestieri]

commit 9f613a5f7eb69cb658e2f97a996270db4129a12e
Author: Enrico Forestieri <for...@lyx.org>
Date:   Sun Nov 9 02:19:00 2014 +0100

    Fix issue with CAS.
    
    See http://thread.gmane.org/gmane.editors.lyx.devel/153516
    This regression was due to a thinko in [43f6b167/lyxgit].

diff --git a/src/mathed/InsetMathHull.cpp b/src/mathed/InsetMathHull.cpp
index 4b9e0ce..55185a2 100644
--- a/src/mathed/InsetMathHull.cpp
+++ b/src/mathed/InsetMathHull.cpp
@@ -1354,7 +1354,7 @@ void InsetMathHull::doExtern(Cursor & cur, FuncRequest & 
func)
                MathData ar;
                if (cur.inMathed() && cur.selection()) {
                        asArray(grabAndEraseSelection(cur), ar);
-               } else if (!pos == cur.cell().empty()) {
+               } else if (pos == cur.cell().size()) {
                        ar = cur.cell();
                        lyxerr << "use whole cell: " << ar << endl;
                } else {