The iPhone 5 will sport a metal back and a screen less than four inches in size, according to a new report. Citing sources from panel suppliers, DigiTimes reports that despite recent rumors of the handset featuring a 4.2-inch panel, it will instead feature a screen that’s either the same 3.5-inches as the current model or 3.7-inches, with a thinner bezel to make the screen look larger. The report also claims that the rear of the phone will be…