[LyX/master] Avoid calling Buffer::getMacro inside the MathMacro copy constructor

[Enrico Forestieri]

commit 4dff1394ab845878f16cb03455477cfb44ceb8cb
Author: Enrico Forestieri <for...@lyx.org>
Date:   Sun Jul 5 20:44:54 2015 +0200

    Avoid calling Buffer::getMacro inside the MathMacro copy constructor
    
    It turns out that it is always better using the copy of the MacroData
    for updating the macro_ pointer to avoid problems related to the cursor
    position.

diff --git a/src/mathed/MathMacro.cpp b/src/mathed/MathMacro.cpp
index 918a989..08f367c 100644
--- a/src/mathed/MathMacro.cpp
+++ b/src/mathed/MathMacro.cpp
@@ -194,15 +194,10 @@ void MathMacro::Private::updateChildren(MathMacro * owner)
        }
 
        if (macro_ && lyxrc.preview == LyXRC::PREVIEW_ON) {
-               // We need to update macro_ by ourselves because in this case
-               // MathData::metrics() is not called when selecting a math inset
-               DocIterator const & pos = macroBackup_.pos();
-               Buffer const * buf = pos.buffer();
-               if (buf && !theBufferList().isLoaded(buf))
-                       buf = 0;
-               macro_ = buf ? buf->getMacro(owner->name(), pos) : 0;
-               if (!macro_)
-                       macro_ = &macroBackup_;
+               // As MathData::metrics() is not called when instant preview is
+               // on, we have to update macro_ by ourselves. In this case, we
+               // simply let it point to the last known good copy of MacroData.
+               macro_ = &macroBackup_;
        }
 }