Support JavaScript window.moveTo/By() and resizeTo/By() (fixes #698)

Adds new CefDisplayHandler::OnContentsBoundsChange and
CefDisplayHandler::GetRootWindowScreenRect callbacks.

cefclient: Implement the above callbacks and call
CefBrowserHost::NotifyScreenInfoChanged when the root window
bounds change.

cefclient: osr: Use real screen bounds by default. Pass
`--fake-screen-bounds` for the old default behavior.

Load https://tests/window in cefclient for additional
implementation details and usage examples.

libcef/browser/chrome/chrome_browser_delegate.h

@@ -94,6 +94,8 @@ class ChromeBrowserDelegate : public cef::BrowserDelegate {
                         const content::OpenURLParams& params,
                         base::OnceCallback<void(content::NavigationHandle&)>&
                             navigation_handle_callback) override;
+  bool SetContentsBoundsEx(content::WebContents* source,
+                           const gfx::Rect& bounds) override;
 
   // WebContentsDelegate methods:
   void WebContentsCreated(content::WebContents* source_contents,