Correct scaling problems with PDF output (issue #11590)

Possible fix for inaccurate PDF output mentioned by issue #11590

The unit px is one point inside the HTML source page but phantomjs handles it without reason as 1/2.54 points. This makes the page smaller than expected when trying to render a page as PDF. Instead 1 point should really be 1 point.

PDFs are not rendered like PNG or other image formats by phantomjs because it uses the printer functionality of Qt+Webkit. But Webkit uses some printer "optimization" to save paper by shrinking the output. Such shrinking results in too small content on a page. Instead no shrinking should be used to have a similar output as raster target formats.