[LyX/master] Fix embarrassing typo

[Jean-Marc Lasgouttes]

commit 058c6750ac83b43819445ccf723283afb850ef91
Author: Jean-Marc Lasgouttes <lasgout...@lyx.org>
Date:   Mon Dec 17 12:28:32 2018 +0100

    Fix embarrassing typo
    
    Not clear whether this caused any bug.
---
 src/Dimension.h |    4 ++--
 1 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/src/Dimension.h b/src/Dimension.h
index 0607be6..0f7fdab 100644
--- a/src/Dimension.h
+++ b/src/Dimension.h
@@ -32,8 +32,8 @@ public:
        void operator+=(Dimension const & dim);
        /// set to empty box
        void clear() { wid = asc = des = 0; }
-       /// check if box is empty
-       bool empty() const { return wid == 0 && asc == 0 && wid == 0; }
+       /// check whether box is empty
+       bool empty() const { return wid == 0 && asc == 0 && des == 0; }
        /// get height
        int height() const { return asc + des; }
        /// get ascent