Revert of [oilpan]: Remove support for tracing off-heap hashmaps.

Source/platform/heap/HeapTest.cpp

Index: Source/platform/heap/HeapTest.cpp
diff --git a/Source/platform/heap/HeapTest.cpp b/Source/platform/heap/HeapTest.cpp
index 1309cddf5f5ba9aba34d6124711fd8468dcc55d5..a50f5361658f0088fa7e032b52315499f2e8b2ef 100644
--- a/Source/platform/heap/HeapTest.cpp
+++ b/Source/platform/heap/HeapTest.cpp
@@ -2017,7 +2017,7 @@
     static OffHeapContainer* create() { return new OffHeapContainer(); }
 
     static const int iterations = 300;
-    static const int deadWrappers = 1500;
+    static const int deadWrappers = 1800;
 
     OffHeapContainer()
     {
@@ -2026,6 +2026,7 @@
             m_vector1.append(ShouldBeTraced(IntWrapper::create(i)));
             m_deque2.append(IntWrapper::create(i));
             m_vector2.append(IntWrapper::create(i));
+            m_hashMap.add(i + 103, IntWrapper::create(i));
             m_ownedVector.append(adoptPtr(new ShouldBeTraced(IntWrapper::create(i))));
         }
 
@@ -2033,6 +2034,7 @@
         Vector<ShouldBeTraced>::iterator v1Iterator(m_vector1.begin());
         Deque<Member<IntWrapper> >::iterator d2Iterator(m_deque2.begin());
         Vector<Member<IntWrapper> >::iterator v2Iterator(m_vector2.begin());
+        HashMap<int, Member<IntWrapper> >::iterator mapIterator(m_hashMap.begin());
         Vector<OwnPtr<ShouldBeTraced> >::iterator ownedVectorIterator(m_ownedVector.begin());
 
         for (int i = 0; i < iterations; i++) {
@@ -2043,16 +2045,21 @@
             EXPECT_EQ(i, d2Iterator->get()->value());
             EXPECT_EQ(i, v2Iterator->get()->value());
             EXPECT_EQ(i, ownedVectorIterator->get()->m_wrapper->value());
+            int value = mapIterator->value.get()->value();
+            EXPECT_LE(0, value);
+            EXPECT_GT(iterations, value);
             ++d1Iterator;
             ++v1Iterator;
             ++d2Iterator;
             ++v2Iterator;
+            ++mapIterator;
             ++ownedVectorIterator;
         }
         EXPECT_EQ(d1Iterator, m_deque1.end());
         EXPECT_EQ(v1Iterator, m_vector1.end());
         EXPECT_EQ(d2Iterator, m_deque2.end());
         EXPECT_EQ(v2Iterator, m_vector2.end());
+        EXPECT_EQ(mapIterator, m_hashMap.end());
         EXPECT_EQ(ownedVectorIterator, m_ownedVector.end());
     }
 
@@ -2062,6 +2069,7 @@
         visitor->trace(m_vector1);
         visitor->trace(m_deque2);
         visitor->trace(m_vector2);
+        visitor->trace(m_hashMap);
         visitor->trace(m_ownedVector);
     }
 
@@ -2069,6 +2077,7 @@
     Vector<ShouldBeTraced> m_vector1;
     Deque<Member<IntWrapper> > m_deque2;
     Vector<Member<IntWrapper> > m_vector2;
+    HashMap<int, Member<IntWrapper> > m_hashMap;
     Vector<OwnPtr<ShouldBeTraced> > m_ownedVector;
 };