Speed-up id look-up for SVG node.
Speed-up id look-up for SVG node.

Since we are iterating all the XML attributes, we find and locate the id
while we are inside the loop. Thus, no need to retrieve the id via
QXmlStreamAttributes::value().

Also, get rid of someId(QSvgAttributes) function and use the 'id' member
variable directly.

Loading tiger.svg (tests/benchmarks/qsvgrenderer) enjoys 1.2% speed-up.

Reviewed-by: Kim

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