Parse all keys as integers *before* calling max
Parse all keys as integers *before* calling max

Fixes atom/atom#1862
atom/text-buffer,whodatninja/text-buffer,atom/text-buffer,pombredanne/text-buffer,pombredanne/text-buffer,jacekkopecky/text-buffer,jacekkopecky/text-buffer,mizchi-sandbox/standalone-atom-editor,mizchi-sandbox/standalone-atom-editor