Revert of [heap] Always use the passed-in collector in CollectGarbage....

Revert of [heap] Always use the passed-in collector in CollectGarbage. (patchset #1 id:1 of https://codereview.chromium.org/2336943003/ )

Reason for revert:
Regresses jank and memory. Revert for offline analysis.

Original issue's description:
> [heap] Always use the passed-in collector in CollectGarbage.
>
> Do not overwrite a collector decision.
>
> BUG=
>
> Committed: https://crrev.com/c19abaddafb5ede5e0d5efbe608b7fc5d7c7fcd0
> Cr-Commit-Position: refs/heads/master@{#39585}

TBR=ulan@chromium.org
# Not skipping CQ checks because original CL landed more than 1 days ago.
BUG=

Review-Url: https://codereview.chromium.org/2369933004
Cr-Commit-Position: refs/heads/master@{#39770}

src/heap/heap.cc

@@ -972,6 +972,22 @@ bool Heap::CollectGarbage(GarbageCollector collector,
     }
   }
 
+  if (collector == MARK_COMPACTOR && !ShouldFinalizeIncrementalMarking() &&
+      !ShouldAbortIncrementalMarking() && !incremental_marking()->IsStopped() &&
+      !incremental_marking()->should_hurry() && FLAG_incremental_marking &&
+      OldGenerationAllocationLimitReached()) {
+    if (!incremental_marking()->IsComplete() &&
+        !mark_compact_collector()->marking_deque_.IsEmpty() &&
+        !FLAG_gc_global) {
+      if (FLAG_trace_incremental_marking) {
+        isolate()->PrintWithTimestamp(
+            "[IncrementalMarking] Delaying MarkSweep.\n");
+      }
+      collector = SCAVENGER;
+      collector_reason = "incremental marking delaying mark-sweep";
+    }
+  }
+
   bool next_gc_likely_to_collect_more = false;
   intptr_t committed_memory_before = 0;