-[WebView _scaleWebView:] should take and origin and scroll the 
document
-and corresponding-
<rdar://problem/8643921>

Reviewed by Simon Fraser.

WebCore: 

Apply the scale to the origin, and set a new scroll position.
* page/Frame.cpp:
(WebCore::Frame::scalePage):
* page/Frame.h:
* WebCore.exp.in:

WebKit/mac: 

* WebView/WebView.mm:
(-[WebView _scaleWebView:atOrigin:]):
* WebView/WebViewPrivate.h:

WebKit2: 

* Shared/API/c/WKSharedAPICast.h:
(WebKit::toImpl):
* UIProcess/API/C/WKPage.cpp:
(WKPageScaleWebView):
* UIProcess/API/C/WKPage.h:
* UIProcess/WebPageProxy.cpp:
(WebKit::WebPageProxy::scaleWebView):
* UIProcess/WebPageProxy.h:
* WebProcess/WebPage/WebPage.cpp:
(WebKit::WebPage::scaleWebView):
* WebProcess/WebPage/WebPage.h:
* WebProcess/WebPage/WebPage.messages.in:



git-svn-id: http://svn.webkit.org/repository/webkit/trunk@71790 268f45cc-cd09-0410-ab3c-d52691b4dbfc