Oilpan: fix reported unit test leaks.

Source/core/dom/DocumentTest.cpp

Index: Source/core/dom/DocumentTest.cpp
diff --git a/Source/core/dom/DocumentTest.cpp b/Source/core/dom/DocumentTest.cpp
index a1c93b2bddfdc3b505d6af4fcf61402022f30883..7e2d35efd229b61e982cf39457504976a4f7ead4 100644
--- a/Source/core/dom/DocumentTest.cpp
+++ b/Source/core/dom/DocumentTest.cpp
@@ -34,6 +34,7 @@
 #include "core/html/HTMLHeadElement.h"
 #include "core/html/HTMLLinkElement.h"
 #include "core/testing/DummyPageHolder.h"
+#include "platform/heap/Handle.h"
 #include <gmock/gmock.h>
 #include <gtest/gtest.h>
 
@@ -45,6 +46,13 @@ class DocumentTest : public ::testing::Test {
 protected:
     virtual void SetUp() OVERRIDE;
 
+#if ENABLE(OILPAN)
+    virtual void TearDown() OVERRIDE
+    {
+        Heap::collectAllGarbage();
+    }
+#endif
+
     Document& document() const { return m_dummyPageHolder->document(); }
     Page& page() const { return m_dummyPageHolder->page(); }