[ic] Cache weak cells containing prototypes in respective PrototypeInfo objects.

src/ic/x64/handler-compiler-x64.cc

Index: src/ic/x64/handler-compiler-x64.cc
diff --git a/src/ic/x64/handler-compiler-x64.cc b/src/ic/x64/handler-compiler-x64.cc
index f386fc5b65f418c53ad323b74868f4dd441f07a8..ef4f411656fc55604db243195b96f39cfdb48c66 100644
--- a/src/ic/x64/handler-compiler-x64.cc
+++ b/src/ic/x64/handler-compiler-x64.cc
@@ -484,8 +484,9 @@ Register PropertyHandlerCompiler::CheckPrototypes(
                  NameDictionary::kNotFound);
 
       if (depth > 1) {
-        // TODO(jkummerow): Cache and re-use weak cell.
-        __ LoadWeakValue(reg, isolate()->factory()->NewWeakCell(current), miss);
+        Handle<WeakCell> weak_cell =
+            Map::GetOrCreatePrototypeWeakCell(current, isolate());
+        __ LoadWeakValue(reg, weak_cell, miss);
       }
       GenerateDictionaryNegativeLookup(masm(), miss, reg, name, scratch1,
                                        scratch2);
@@ -504,7 +505,9 @@ Register PropertyHandlerCompiler::CheckPrototypes(
 
   bool return_holder = return_what == RETURN_HOLDER;
   if (return_holder && depth != 0) {
-    __ LoadWeakValue(reg, isolate()->factory()->NewWeakCell(current), miss);
+    Handle<WeakCell> weak_cell =
+        Map::GetOrCreatePrototypeWeakCell(current, isolate());
+    __ LoadWeakValue(reg, weak_cell, miss);
   }
 
   // Return the register containing the holder.