Revert "Move Math.textFromCharCode to the text category."
Revert "Move Math.textFromCharCode to the text category."

This reverts commit 8efef6c9cd09a8eb122bf36f7a5352b87b3d5a7f.

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