Mark test-profile-generator/RecordStackTraceAtStartProfiling as always passing

The test should be stable now.

Drive-by: removed test-heap-profiler/HeapSnapshotsDiff from cctest.status as there is no such test

BUG=None
R=jkummerow@chromium.org

Review URL: https://codereview.chromium.org/15786005

git-svn-id: https://v8.googlecode.com/svn/branches/bleeding_edge@14839 ce2b1a6d-e550-0410-aec6-3dcde31c8c00