Added -SourceLevel auto to match runtime vm spec version. Also -SourceLevel auto is now the default, otherwise devmode would choke on class files it itself compiled. Change-Id: Ife59a3f5137f0cdd51a9acae99aea4d3a5eae837 (cherry picked from commit 8c5e655445b7bfc60b06f277640f98d7b565eae6)