Dialog size should fit the screen in case it's bigger than the view pane

[Sa'ar Zac Elias]

FUP of #5084.
If the dialog size is bigger than the view pane, it should be reduced to fit the view pane. We should cover the resize event as well.

[Jakub Ś]

1. Add the below code to editor1 in the replacebycode sample;

   { extraPlugins : 'mybutton', toolbar :[ ['mybutton'] ] }
   

2. Add plug-in mybutton from the attachment
3. Plug-in has width and height set to 3300.
4. Open dialog by clicking on toolbar button.

Result: width of the dialog seems to fit the view pane (from CKE 3.1) but height doesn't. There is even no way to scroll down to OK and Cancel buttons.