Oilpan: Add trace events for the GC marking and sweeping phases.

Source/bindings/core/v8/V8GCController.cpp

Index: Source/bindings/core/v8/V8GCController.cpp
diff --git a/Source/bindings/core/v8/V8GCController.cpp b/Source/bindings/core/v8/V8GCController.cpp
index 69add90828c3f88a729b9376ffd7aed9354c9fa6..4973a477c3bfce6b39788f15d84483dd0d930434 100644
--- a/Source/bindings/core/v8/V8GCController.cpp
+++ b/Source/bindings/core/v8/V8GCController.cpp
@@ -403,7 +403,7 @@ void V8GCController::gcEpilogue(v8::GCType type, v8::GCCallbackFlags flags)
         // to collect all garbage, you need to wait until the next event loop.
         // Regarding (2), it would be OK in practice to trigger only one GC per gcEpilogue, because
         // GCController.collectAll() forces 7 V8's GC.
-        Heap::collectGarbage(ThreadState::HeapPointersOnStack);
+        Heap::collectGarbage(ThreadState::HeapPointersOnStack, ThreadState::ForcedGC);
 
         // Forces a precise GC at the end of the current event loop.
         Heap::setForcePreciseGCForTesting();