bug 1079932 - Handle more whitespace in Spec2
bug 1079932 - Handle more whitespace in Spec2

This line in https://developer.mozilla.org/en-US/docs/Template:Spec2
was breaking tools/load_spec_data.py:

  'Unhandled Promise Rejection': 'ED',

Adjust the regex to handle the optional space in these lines.

mdn/browsercompat,jwhitlock/web-platform-compat,renoirb/browsercompat,renoirb/browsercompat,jwhitlock/web-platform-compat,mdn/browsercompat,jwhitlock/web-platform-compat,mdn/browsercompat,renoirb/browsercompat