TextEditor: Do not use deleted TextMarks.
TextEditor: Do not use deleted TextMarks.

Task-number: QTCREATORBUG-13136
Change-Id: I12e7d16012bc6118cc5907dd805dedb41414aa52
Reviewed-by: Nikolai Kosjar <9571db158ca61a0d070db010803474231fa0cbab@digia.com>
Reviewed-by: David Schulz <f07954e8cc0c222cd136162588d217f330598215@digia.com>

farseerri/git_code,danimo/qt-creator,Distrotech/qtcreator,amyvmiwei/qt-creator,amyvmiwei/qt-creator,Distrotech/qtcreator,kuba1/qtcreator,xianian/qt-creator,kuba1/qtcreator,danimo/qt-creator,martyone/sailfish-qtcreator,farseerri/git_code,Distrotech/qtcreator,martyone/sailfish-qtcreator,danimo/qt-creator,amyvmiwei/qt-creator,xianian/qt-creator,xianian/qt-creator,danimo/qt-creator,martyone/sailfish-qtcreator,Distrotech/qtcreator,farseerri/git_code,farseerri/git_code,danimo/qt-creator,martyone/sailfish-qtcreator,kuba1/qtcreator,amyvmiwei/qt-creator,xianian/qt-creator,Distrotech/qtcreator,xianian/qt-creator,Distrotech/qtcreator,farseerri/git_code,danimo/qt-creator,farseerri/git_code,danimo/qt-creator,martyone/sailfish-qtcreator,martyone/sailfish-qtcreator,AltarBeastiful/qt-creator,AltarBeastiful/qt-creator,xianian/qt-creator,amyvmiwei/qt-creator,kuba1/qtcreator,xianian/qt-creator,farseerri/git_code,kuba1/qtcreator,martyone/sailfish-qtcreator,Distrotech/qtcreator,kuba1/qtcreator,xianian/qt-creator,amyvmiwei/qt-creator,xianian/qt-creator,danimo/qt-creator,amyvmiwei/qt-creator,AltarBeastiful/qt-creator,kuba1/qtcreator,danimo/qt-creator,kuba1/qtcreator,farseerri/git_code,AltarBeastiful/qt-creator,AltarBeastiful/qt-creator,kuba1/qtcreator,AltarBeastiful/qt-creator,AltarBeastiful/qt-creator,martyone/sailfish-qtcreator,amyvmiwei/qt-creator,AltarBeastiful/qt-creator,martyone/sailfish-qtcreator