Revert https://codereview.chromium.org/1291903002 (protobuf roll).

third_party/protobuf/vsprojects/convert2008to2005.sh

+#! /bin/sh -e
+
+# This script downgrades MSVC 2008 projects to MSVC 2005 projects, allowing
+# people with MSVC 2005 to open them.  Otherwise, MSVC 2005 simply refuses to
+# open projects created with 2008.  We run this as part of our release process.
+# If you obtained the code direct from version control and you want to use
+# MSVC 2005, you may have to run this manually.  (Hint:  Use Cygwin or MSYS.)
+
+for file in *.sln; do
+  echo "downgrading $file..."
+  sed -i -re 's/Format Version 10.00/Format Version 9.00/g;
+              s/Visual Studio 2008/Visual Studio 2005/g;' $file
+done
+
+for file in *.vcproj; do
+  echo "downgrading $file..."
+  sed -i -re 's/Version="9.00"/Version="8.00"/g;' $file
+done
+
+# Yes, really, that's it.