Oilpan: In ASan, poison all unmarked objects before start sweeping

Source/platform/heap/Heap.h

Index: Source/platform/heap/Heap.h
diff --git a/Source/platform/heap/Heap.h b/Source/platform/heap/Heap.h
index 161a8ffe92a3a20e4c30a10384871417b598c1ff..e329bd8144d5b95e4d93ceec49744818a7dab439 100644
--- a/Source/platform/heap/Heap.h
+++ b/Source/platform/heap/Heap.h
@@ -384,6 +384,9 @@ public:
     virtual void removeFromHeap() = 0;
     virtual void sweep() = 0;
     virtual void markUnmarkedObjectsDead() = 0;
+#if defined(ADDRESS_SANITIZER)
+    virtual void poisonUnmarkedObjects() = 0;
+#endif
     // Check if the given address points to an object in this
     // heap page. If so, find the start of that object and mark it
     // using the given Visitor. Otherwise do nothing. The pointer must
@@ -468,6 +471,9 @@ public:
     virtual void removeFromHeap() override;
     virtual void sweep() override;
     virtual void markUnmarkedObjectsDead() override;
+#if defined(ADDRESS_SANITIZER)
+    virtual void poisonUnmarkedObjects() override;
+#endif
     virtual void checkAndMarkPointer(Visitor*, Address) override;
     virtual void markOrphaned() override;
 #if ENABLE(GC_PROFILING)
@@ -496,10 +502,6 @@ public:
     NormalPageHeap* heapForNormalPage();
     void clearObjectStartBitMap();
 
-#if defined(ADDRESS_SANITIZER)
-    void poisonUnmarkedObjects();
-#endif
-
 private:
     HeapObjectHeader* findHeaderFromAddress(Address);
     void populateObjectStartBitMap();
@@ -531,6 +533,9 @@ public:
     virtual void removeFromHeap() override;
     virtual void sweep() override;
     virtual void markUnmarkedObjectsDead() override;
+#if defined(ADDRESS_SANITIZER)
+    virtual void poisonUnmarkedObjects() override;
+#endif
     virtual void checkAndMarkPointer(Visitor*, Address) override;
     virtual void markOrphaned() override;
 
@@ -741,6 +746,9 @@ public:
     size_t objectPayloadSizeForTesting();
     void prepareHeapForTermination();
     void prepareForSweep();
+#if defined(ADDRESS_SANITIZER)
+    void poisonUnmarkedObjects();
+#endif
     Address lazySweep(size_t, size_t gcInfoIndex);
     void sweepUnsweptPage();
     // Returns true if we have swept all pages within the deadline.