Run core tests in Safari. Partially addresses https://github.com/pyodide/pyodide/issues/989

It runs, but there are several test failures, I'll open separate issues about those.
package:
  name: traits
  version: 6.3.2
  top-level:
    - traits
source:
  sha256: 4520ef4a675181f38be4a5bab1b1d5472691597fe2cfe4faf91023e89407e2c6
  url: https://files.pythonhosted.org/packages/38/52/1b43e67cd21e7a2bad8d72f80d4280f8f02b65c154589f91e7b17383bdb5/traits-6.3.2.tar.gz
about:
  home: http://docs.enthought.com/traits
  PyPI: https://pypi.org/project/traits
  summary: Observable typed attributes for Python classes
  license: BSD

package:
  name: traits
  version: 6.3.2
  top-level:
    - traits
source:
  sha256: 4520ef4a675181f38be4a5bab1b1d5472691597fe2cfe4faf91023e89407e2c6
  url: https://files.pythonhosted.org/packages/38/52/1b43e67cd21e7a2bad8d72f80d4280f8f02b65c154589f91e7b17383bdb5/traits-6.3.2.tar.gz
about:
  home: http://docs.enthought.com/traits
  PyPI: https://pypi.org/project/traits
  summary: Observable typed attributes for Python classes
  license: BSD
