Implement ES6 symbol registry and predefined symbols

src/heap.cc

Index: src/heap.cc
diff --git a/src/heap.cc b/src/heap.cc
index e2b83f507a999a4103c23b9f26ddb7c615383a0c..0691947600c1923049eb3e02fa65422c5b2d369e 100644
--- a/src/heap.cc
+++ b/src/heap.cc
@@ -3288,6 +3288,14 @@ bool Heap::CreateInitialObjects() {
   }
   set_undefined_cell(Cell::cast(obj));
 
+  // Allocate objects to hold symbol registry.
+  { MaybeObject* maybe_obj = AllocateMap(JS_OBJECT_TYPE, JSObject::kHeaderSize);
+    if (!maybe_obj->ToObject(&obj)) return false;
+    maybe_obj = AllocateJSObjectFromMap(Map::cast(obj));
+    if (!maybe_obj->ToObject(&obj)) return false;
+  }
+  set_symbol_registry(JSObject::cast(obj));
+
   // Allocate object to hold object observation state.
   { MaybeObject* maybe_obj = AllocateMap(JS_OBJECT_TYPE, JSObject::kHeaderSize);
     if (!maybe_obj->ToObject(&obj)) return false;