Implement QWebPage::setDevicePixelRatio to allow wkhtmltopdf to set the device pixel ratio.

Author: Peter van der Tak

src/3rdparty/webkit/Source/WebKit/qt/Api/qwebpage.cpp

@@ -3215,6 +3215,11 @@ bool QWebPage::isContentEditable() const
     return d->page->isEditable();
 }
 
+void QWebPage::setDevicePixelRatio(qreal devicePixelRatio)
+{
+    d->pixelRatio = devicePixelRatio;
+}
+
 /*!
     \property QWebPage::forwardUnsupportedContent
     \brief whether QWebPage should forward unsupported content

src/3rdparty/webkit/Source/WebKit/qt/Api/qwebpage.h

@@ -308,6 +308,8 @@ class QWEBKIT_EXPORT QWebPage : public QObject {
     void setContentEditable(bool editable);
     bool isContentEditable() const;
 
+    void setDevicePixelRatio(qreal devicePixelRatio);
+
 #ifndef QT_NO_CONTEXTMENU
     bool swallowContextMenuEvent(QContextMenuEvent *event);
 #endif