IFrame workspace fixes (#4595)
IFrame workspace fixes (#4595)

* IFrame workspace fixes

* Linting

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