Remove object grouping leftovers

BUG=v8:5828

Change-Id: I1a75c06ba80a39b28b74870c3e3be4d5e2ec3712
Reviewed-on: https://chromium-review.googlesource.com/480299Reviewed-by: Jochen Eisinger <jochen@chromium.org>
Commit-Queue: Michael Lippautz <mlippautz@chromium.org>
Cr-Commit-Position: refs/heads/master@{#44684}

src/flag-definitions.h

@@ -895,10 +895,6 @@ DEFINE_BOOL(clear_exceptions_on_js_entry, false,
 DEFINE_INT(histogram_interval, 600000,
            "time interval in ms for aggregating memory histograms")
 
-// global-handles.cc
-DEFINE_BOOL(trace_object_groups, false,
-            "print object groups detected during each garbage collection")
-
 // heap-snapshot-generator.cc
 DEFINE_BOOL(heap_profiler_trace_objects, false,
             "Dump heap object allocations/movements/size_updates")

tools/eval_gc_time.sh

@@ -86,7 +86,6 @@ INTERESTING_NEW_GEN_KEYS="\
   old_new \
   code \
   semispace \
-  object_groups \
 "
 
 INTERESTING_OLD_GEN_KEYS="\