Fix to QSyntaxHighlighter not rehighlighting enough
Fix to QSyntaxHighlighter not rehighlighting enough

When entire blocks get deleted, the last block for rehighlighting
would be the block _before_ the deleted blocks. This is wrong,
since the deleted blocks could have contained characters which
affect the state. The patch lets the highlighter check for one
more character.

Reviewed-by: thorbjorn
(cherry picked from commit fd2090b925f46bc0dfffd34612a9bfcd276c3266)

pruiz/wkhtmltopdf-qt,igor-sfdc/qt-wk,pruiz/wkhtmltopdf-qt,igor-sfdc/qt-wk,igor-sfdc/qt-wk,igor-sfdc/qt-wk,pruiz/wkhtmltopdf-qt,igor-sfdc/qt-wk,igor-sfdc/qt-wk,pruiz/wkhtmltopdf-qt,pruiz/wkhtmltopdf-qt,igor-sfdc/qt-wk,pruiz/wkhtmltopdf-qt,pruiz/wkhtmltopdf-qt,igor-sfdc/qt-wk,pruiz/wkhtmltopdf-qt,pruiz/wkhtmltopdf-qt,igor-sfdc/qt-wk,pruiz/wkhtmltopdf-qt,pruiz/wkhtmltopdf-qt,igor-sfdc/qt-wk,igor-sfdc/qt-wk