4243978: (ref) Race condition in Reference.enqueue() 4268317: (ref) Reference.isEnqueued() can return true when instance not enqueued Summary: The reference handler now declares, and assumes, that the discovered field, rather than the next field, is (to be) used to link the entries in the pending list, thus allowing a reference object to be safely enqueued even while it is in the pending state. Also added slightly modified regression tests from the two bug reports. Reviewed-by: mchung, alanb, jcoomes

^build/
^dist/
/nbproject/private/
^src/share/tools/hsdis/build/
^src/share/tools/IdealGraphVisualizer/[a-zA-Z0-9]*/build/
^src/share/tools/IdealGraphVisualizer/build/
^src/share/tools/IdealGraphVisualizer/dist/
^.hgtip
.DS_Store