Refactor recording of safepoints.

Refactor recording of safepoints.

Refactor SafepointTableBuilder::DefineSafepoint and ARM LCodeGen::RecordSafepoint to use an enum for different kinds of safepoints. This change removes a lot of duplicated code and makes it easier to include new kinds of safepoints in the future. The remaining variants of LCodeGen::RecordSafepoint remain as a convinient way to record common safepoint kinds.

BUG=http://code.google.com/p/v8/issues/detail?id=1043
TEST=none

Review URL: http://codereview.chromium.org/6341008

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@6505 ce2b1a6d-e550-0410-aec6-3dcde31c8c00