Xcode: Remove dead code

Variable 'ext' already checked for equality to "xib" so remove the
branch that will never be executed.
Xcode: Fix storyboard view

Images and xib files must have 'lastKnownFileType' attribute to be
displayed correctly. If xib file has attribute 'explicitFileType' it is
displayed as raw xml. If static image has attribute 'explicitFileType'
it is displayed as question mark on storyboard.
Merge topic 'xcode-storyboard-view' into next

1ce02ebf Xcode: Fix storyboard view
d9f1f917 Xcode: Remove dead code