Use the partition allocator and run the test in debug too.

Source/core/platform/Partitions.cpp

Index: Source/core/platform/Partitions.cpp
diff --git a/Source/core/platform/Partitions.cpp b/Source/core/platform/Partitions.cpp
index 609672b70424436c0ca835c78de6e96cbc45dc53..3630819918d258c4b4e029f34bf540b6c3f4d79e 100644
--- a/Source/core/platform/Partitions.cpp
+++ b/Source/core/platform/Partitions.cpp
@@ -44,7 +44,10 @@ void Partitions::init()
 
 void Partitions::shutdown()
 {
-    partitionAllocShutdown(&m_objectModelRoot);
+    // We could ASSERT here for a memory leak within the partition, but it leads
+    // to very hard to diagnose ASSERTs, so it's best to leave leak checking for
+    // the valgrind and heapcheck bots, which run without partitions.
+    (void) partitionAllocShutdown(&m_objectModelRoot);
 }
 #endif