Dwindling supplies of Apple’s iPhone 4 Bumper case in certain regions may be pointing to an impending discontinuation of the line, according to a new report. Citing information received from informant “Mr. X”, 9to5Mac reports that stock of Apple’s in-house iPhone 4 case is constrained in certain regions, which it takes as an indication that Apple plans to either update or discontinue the line. The report notes that the next…