Initilize the WebPageProxy intrinsicDeviceScaleFactor on creation of the WKView.

Initilize the WebPageProxy intrinsicDeviceScaleFactor on creation of the WKView.

If WKView was created and loaded a page with canvas elements before beinging moved
to a window, the canvas elements would be locked in at a pixel ratio of 1. With this
change the WKView will use the main screen's pixel ratio until it moves to a window.

Reviewed by Anders Carlsson.

* UIProcess/API/mac/WKView.mm:
(-[WKView initWithFrame:contextRef:pageGroupRef:]): Call setIntrinsicDeviceScaleFactor.

git-svn-id: http://svn.webkit.org/repository/webkit/trunk@107017 268f45cc-cd09-0410-ab3c-d52691b4dbfc