Remove redundant and meaningless comments in hotspot/share/opto directory.

They are either
1. Repeat the function name that the function they comment for.
2. Makes no sense, e.g. //----Idealize----

Original CC-style code (if( test ),call( arg )) can be formatted in one go, instead of formatting the near code when someone touches them. But this may form a big patch, and it confuses code blame, so I left this work until we reach a consensus.