PDFPlugin: Update PDFLayerController's scale factors earlier
https://bugs.webkit.org/show_bug.cgi?id=114843

Reviewed by Simon Fraser.

Inform PDFLayerController of the initial page/device scale factors so that
it renders at the correct scale the first time, instead of first rendering
at 1x and then flashing to 2x (on 2x devices).

* WebProcess/Plugins/PDF/PDFPlugin.mm:
(WebKit::PDFPlugin::pdfDocumentDidLoad):


git-svn-id: http://svn.webkit.org/repository/webkit/trunk@148719 268f45cc-cd09-0410-ab3c-d52691b4dbfc