heap: Enable concurrent sweeping

Bug: 967258
Change-Id: Icceb19ca3de17b42ed9755a433f7996d34add137
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1712565Reviewed-by: Michael Lippautz <mlippautz@chromium.org>
Reviewed-by: Kentaro Hara <haraken@chromium.org>
Commit-Queue: Anton Bikineev <bikineev@chromium.org>
Cr-Commit-Position: refs/heads/master@{#679599}

third_party/blink/common/features.cc

@@ -330,7 +330,7 @@ const base::Feature kBlinkHeapConcurrentMarking{
     "BlinkHeapConcurrentMarking", base::FEATURE_DISABLED_BY_DEFAULT};
 // Enables concurrently sweeping Blink's heap.
 const base::Feature kBlinkHeapConcurrentSweeping{
-    "BlinkHeapConcurrentSweeping", base::FEATURE_DISABLED_BY_DEFAULT};
+    "BlinkHeapConcurrentSweeping", base::FEATURE_ENABLED_BY_DEFAULT};
 // Enables incrementally marking Blink's heap.
 const base::Feature kBlinkHeapIncrementalMarking{
     "BlinkHeapIncrementalMarking", base::FEATURE_ENABLED_BY_DEFAULT};