### Version v2.5.0 ### Platform .NET Framework 4.6.2 ### Steps to reproduce - Use .NET Framework 4.62 - Install System.Memory package - Install PolyShim - Try to use `ReadOnlySpan<T>.Contains(T value)` ### Details - Expected behavior: compiles and runs - Actual behavior: compile error; Contains cannot be found. ### Checklist - [x] I have looked through existing issues to make sure that this bug has not been reported before - [x] I have provided a descriptive title for this issue - [x] I have made sure that this bug is reproducible on the latest version of the package - [x] I have provided all the information needed to reproduce this bug as efficiently as possible - [ ] I have sponsored this project