removing browser.tsx (#3148)
removing browser.tsx (#3148)


playi/pxt,Microsoft/pxt,switch-education/pxt,playi/pxt,Microsoft/pxt,switchinnovations/pxt,switchinnovations/pxt,switchinnovations/pxt,Microsoft/pxt,Microsoft/pxt,Microsoft/pxt,switchinnovations/pxt,switch-education/pxt,playi/pxt,switch-education/pxt,switch-education/pxt,playi/pxt,switch-education/pxt