Optimize the equality check case of ICCompare stubs.

src/heap.h

Index: src/heap.h
===================================================================
--- src/heap.h	(revision 9957)
+++ src/heap.h	(working copy)
@@ -136,6 +136,7 @@
   V(JSObject, message_listeners, MessageListeners)                             \
   V(Foreign, prototype_accessors, PrototypeAccessors)                          \
   V(NumberDictionary, code_stubs, CodeStubs)                                   \
+  V(NumberDictionary, compare_stubs_known_objects, CompareStubsKnown)          \
   V(NumberDictionary, non_monomorphic_cache, NonMonomorphicCache)              \
   V(PolymorphicCodeCache, polymorphic_code_cache, PolymorphicCodeCache)        \
   V(Code, js_entry_code, JsEntryCode)                                          \
@@ -1127,6 +1128,12 @@
     roots_[kCodeStubsRootIndex] = value;
   }
 
+  // Sets the compare_stubs_known_objects (only used when expanding
+  // the dictionary).
+  void public_set_compare_stubs_known_objects(NumberDictionary* value) {
+    roots_[kCompareStubsKnownRootIndex] = value;
+  }
+
   // Support for computing object sizes for old objects during GCs. Returns
   // a function that is guaranteed to be safe for computing object sizes in
   // the current GC phase.