This broke tons of examples on Chrome/Android...

- This provides better results for subdivisions of triangles only
- Subdivision examples looks much better now
- Fixes #4455, #3663
- Known issues: doesnt handle UVs, sharp, and semi-sharp edges for now

Fixed issues in the triangulateShape method (a for..in loop was used where a sequential for loop is required). 
A for..in loop should be avoided when using array like objects, because it also enumerates inherited properties and iteration order is not guaranteed.