Revert "[Preferences Refactor] Remove window size combo box from graphics preferences"

The issue wasn't the resolution box, and it apparently has its uses.
This reverts commit ac106b0aff3cb0c710b6473d7582e2d8f6b6def4.

Conflicts:
	indra/newview/skins/default/xui/en-us/panel_preferences_graphics1.xml