Revert of Oilpan: Enable lazy sweeping on non-oilpan builds

Source/platform/heap/ThreadState.cpp

Index: Source/platform/heap/ThreadState.cpp
diff --git a/Source/platform/heap/ThreadState.cpp b/Source/platform/heap/ThreadState.cpp
index 5e97927b5ef18878a0b9e42d8c3e15c9c49ec4b0..699866a4516830374b32646ac8351c86a8c97e33 100644
--- a/Source/platform/heap/ThreadState.cpp
+++ b/Source/platform/heap/ThreadState.cpp
@@ -676,7 +676,10 @@
     if (!isMainThread())
         return;
 
+    // TODO(haraken): Remove this. Lazy sweeping is not yet enabled in non-oilpan builds.
+#if ENABLE(OILPAN)
     Platform::current()->currentThread()->scheduler()->postIdleTask(FROM_HERE, WTF::bind<double>(&ThreadState::performIdleLazySweep, this));
+#endif
 }
 
 void ThreadState::schedulePreciseGC()
@@ -901,6 +904,7 @@
 #endif
 #endif
 
+#if ENABLE(OILPAN)
     if (gcState() == EagerSweepScheduled) {
         // Eager sweeping should happen only in testing.
         setGCState(Sweeping);
@@ -910,6 +914,12 @@
         setGCState(Sweeping);
         scheduleIdleLazySweep();
     }
+#else
+    // FIXME: For now, we disable lazy sweeping in non-oilpan builds
+    // to avoid unacceptable behavior regressions on trunk.
+    setGCState(Sweeping);
+    completeSweep();
+#endif
 
 #if ENABLE(GC_PROFILING)
     snapshotFreeListIfNecessary();