[LyX/master] Pass proper text to TeXOnePar in Paragrapgh::Private::validate

[Juergen Spitzmueller]

commit 4f884fc92d31651d15896e51fbe239772a0bede9
Author: Juergen Spitzmueller <sp...@lyx.org>
Date:   Sat Apr 20 17:51:06 2019 +0200

    Pass proper text to TeXOnePar in Paragrapgh::Private::validate
    
    This fixes InPreamble layouts in insets (#11557)
---
 src/Paragraph.cpp |    3 ++-
 1 files changed, 2 insertions(+), 1 deletions(-)

diff --git a/src/Paragraph.cpp b/src/Paragraph.cpp
index cdd6b23..4e36f7f 100644
--- a/src/Paragraph.cpp
+++ b/src/Paragraph.cpp
@@ -1351,7 +1351,8 @@ void Paragraph::Private::validate(LaTeXFeatures & 
features) const
                otexstringstream os;
                os << layout_->preamble();
                size_t const length = os.length();
-               TeXOnePar(buf, buf.text(), 
buf.getParFromID(owner_->id()).pit(), os,
+               TeXOnePar(buf, 
*inset_owner_->getText(int(buf.getParFromID(owner_->id()).idx())),
+                         buf.getParFromID(owner_->id()).pit(), os,
                          features.runparams(), string(), 0, -1, true);
                if (os.length() > length)
                        features.addPreambleSnippet(os.release(), true);