Fix secondary stub cache and add a test for the stub cache lookups.

src/serialize.cc

Index: src/serialize.cc
===================================================================
--- src/serialize.cc	(revision 10860)
+++ src/serialize.cc	(working copy)
@@ -273,14 +273,22 @@
       STUB_CACHE_TABLE,
       2,
       "StubCache::primary_->value");
+  Add(stub_cache->map_reference(StubCache::kPrimary).address(),
+      STUB_CACHE_TABLE,
+      3,
+      "StubCache::primary_->map");
   Add(stub_cache->key_reference(StubCache::kSecondary).address(),
       STUB_CACHE_TABLE,
-      3,
+      4,
       "StubCache::secondary_->key");
   Add(stub_cache->value_reference(StubCache::kSecondary).address(),
       STUB_CACHE_TABLE,
-      4,
+      5,
       "StubCache::secondary_->value");
+  Add(stub_cache->map_reference(StubCache::kSecondary).address(),
+      STUB_CACHE_TABLE,
+      6,
+      "StubCache::secondary_->map");
 
   // Runtime entries
   Add(ExternalReference::perform_gc_function(isolate).address(),