WeakHashTable::Lookup() handlified and ObjectHashTable's interface cleaned up.

src/lithium-codegen.cc

Index: src/lithium-codegen.cc
diff --git a/src/lithium-codegen.cc b/src/lithium-codegen.cc
index 9186605eb6f28f9be31aef1fde18c77ef8c8c7ae..b5602185e1afc0cdca9df2feadcfdd66cb0ceaad 100644
--- a/src/lithium-codegen.cc
+++ b/src/lithium-codegen.cc
@@ -155,7 +155,7 @@ static void AddWeakObjectToCodeDependency(Isolate* isolate,
                                           Handle<Code> code) {
   Heap* heap = isolate->heap();
   heap->EnsureWeakObjectToCodeTable();
-  Handle<DependentCode> dep(heap->LookupWeakObjectToCodeDependency(*object));
+  Handle<DependentCode> dep(heap->LookupWeakObjectToCodeDependency(object));
   dep = DependentCode::Insert(dep, DependentCode::kWeakCodeGroup, code);
   heap->AddWeakObjectToCodeDependency(object, dep);
 }