[promises] port NewPromiseCapability to TF

src/heap/heap.cc

Index: src/heap/heap.cc
diff --git a/src/heap/heap.cc b/src/heap/heap.cc
index 63a50f3c065214182cea28d92b3f7c22b88bf802..f996922b1a80647d9a82fdb8086ef4313c789c46 100644
--- a/src/heap/heap.cc
+++ b/src/heap/heap.cc
@@ -2270,6 +2270,9 @@ bool Heap::CreateInitialMaps() {
     ALLOCATE_MAP(ODDBALL_TYPE, Oddball::kSize, optimized_out);
     ALLOCATE_MAP(ODDBALL_TYPE, Oddball::kSize, stale_register);
 
+    ALLOCATE_MAP(JS_PROMISE_CAPABILITY_TYPE, JSPromiseCapability::kSize,
+                 js_promise_capability);
+
     for (unsigned i = 0; i < arraysize(string_type_table); i++) {
       const StringTypeTable& entry = string_type_table[i];
       {
@@ -2876,6 +2879,42 @@ void Heap::CreateInitialObjects() {
 
   // Initialize compilation cache.
   isolate_->compilation_cache()->Clear();
+
+  // Finish creating JSPromiseCapabilityMap
+  {
+    // TODO(caitp): This initialization can be removed once PromiseCapability
+    // object is no longer used by builtins implemented in javascript.
+    Handle<Map> map = factory->js_promise_capability_map();
+    map->set_inobject_properties_or_constructor_function_index(3);
+
+    Map::EnsureDescriptorSlack(map, 3);
+
+    PropertyAttributes attrs =
+        static_cast<PropertyAttributes>(READ_ONLY | DONT_DELETE);
+    {  // promise
+      Descriptor d = Descriptor::DataField(factory->promise_string(),
+                                           JSPromiseCapability::kPromiseIndex,
+                                           attrs, Representation::Tagged());
+      map->AppendDescriptor(&d);
+    }
+
+    {  // resolve
+      Descriptor d = Descriptor::DataField(factory->resolve_string(),
+                                           JSPromiseCapability::kResolveIndex,
+                                           attrs, Representation::Tagged());
+      map->AppendDescriptor(&d);
+    }
+
+    {  // reject
+      Descriptor d = Descriptor::DataField(factory->reject_string(),
+                                           JSPromiseCapability::kRejectIndex,
+                                           attrs, Representation::Tagged());
+      map->AppendDescriptor(&d);
+    }
+
+    map->set_is_extensible(false);
+    set_js_promise_capability_map(*map);
+  }
 }
 
 bool Heap::RootCanBeWrittenAfterInitialization(Heap::RootListIndex root_index) {