8153666: Optimize Formatter.formatMessage
Summary: This patch brings a small optimization that removes needless synchronization in Formatter.formatMessage. It also fixes the code that decides whether to call MessageFormat, and brings a small clarification to the API documentation on the conditions when that will happen.
Reviewed-by: rriggs, martin

8054834: Modular Source Code
Reviewed-by: alanb, chegar, ihse, mduigou
Contributed-by: alan.bateman@oracle.com, alex.buckley@oracle.com, chris.hegarty@oracle.com, erik.joelsson@oracle.com, jonathan.gibbons@oracle.com, karen.kinnear@oracle.com, magnus.ihse.bursie@oracle.com, mandy.chung@oracle.com, mark.reinhold@oracle.com, paul.sandoz@oracle.com