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_host_impl.h

@@ -84,7 +84,6 @@ class ChromeBrowserHostImpl : public CefBrowserHostBase {
   bool IsWindowRenderingDisabled() override { return false; }
   void WasResized() override;
   void WasHidden(bool hidden) override;
-  void NotifyScreenInfoChanged() override;
   void Invalidate(PaintElementType type) override;
   void SendExternalBeginFrame() override;
   void SendTouchEvent(const CefTouchEvent& event) override;