feat: remove unnecessary 'tryParse' on parseDouble

[fransdhinta]

There is some issue while calling parseDouble like this: https://github.com/dnfield/vector_graphics/issues/209 I suggest a fix to change the return of parseDouble to always double.tryParse so that it will return null instead of throwing an error if it parses an invalid String

[zanderso]

Hi there, The Flutter team is now maintaining these packages in the flutter/packages repository at packages/vector_graphics and packages/vector_graphics_compiler. We'd appreciate it if you could direct this PR to those locations instead. Thanks!