Remove functions_cache_ and it's references as it is not being used anymore.

vm/object.cc

Index: vm/object.cc
===================================================================
--- vm/object.cc	(revision 10541)
+++ vm/object.cc	(working copy)
@@ -1186,13 +1186,6 @@
 }
 
 
-void Class::InitFunctionsCache() const {
-  // TODO(srdjan): Make functions_cache growable and start with smaller size.
-  StorePointer(&raw_ptr()->functions_cache_,
-               Array::New(FunctionsCache::kNumEntries * 32, Heap::kOld));
-}
-
-
 bool Class::HasInstanceFields() const {
   const Array& field_array = Array::Handle(fields());
   Field& field = Field::Handle();
@@ -1680,12 +1673,6 @@
 }
 
 
-void Class::set_functions_cache(const Array& value) const {
-  ASSERT(!value.IsNull());
-  StorePointer(&raw_ptr()->functions_cache_, value.raw());
-}
-
-
 RawArray* Class::constants() const {
   return raw_ptr()->constants_;
 }