[modules] Basic support of exports

src/contexts.cc

Index: src/contexts.cc
diff --git a/src/contexts.cc b/src/contexts.cc
index ea4730042fc468ed0623b9a0198a6e095411895c..0147296bf8846f6e851561b874e7bd0cdad1d125 100644
--- a/src/contexts.cc
+++ b/src/contexts.cc
@@ -57,7 +57,8 @@ bool ScriptContextTable::Lookup(Handle<ScriptContextTable> table,
 
 
 bool Context::is_declaration_context() {
-  if (IsFunctionContext() || IsNativeContext() || IsScriptContext()) {
+  if (IsFunctionContext() || IsNativeContext() || IsScriptContext() ||
+      IsModuleContext()) {
     return true;
   }
   if (!IsBlockContext()) return false;
@@ -110,7 +111,7 @@ JSReceiver* Context::extension_receiver() {
 
 
 ScopeInfo* Context::scope_info() {
-  DCHECK(IsModuleContext() || IsScriptContext() || IsBlockContext());
+  DCHECK(IsScriptContext() || IsBlockContext());
   HeapObject* object = extension();
   if (object->IsContextExtension()) {
     DCHECK(IsBlockContext());
@@ -119,6 +120,13 @@ ScopeInfo* Context::scope_info() {
   return ScopeInfo::cast(object);
 }
 
+JSModule* Context::module() {
+  Context* current = this;
+  while (!current->IsModuleContext()) {
+    current = current->previous();
+  }
+  return JSModule::cast(current->extension());
+}
 
 String* Context::catch_name() {
   DCHECK(IsCatchContext());
@@ -185,6 +193,7 @@ Handle<Object> Context::Lookup(Handle<String> name, ContextLookupFlags flags,
                                int* index, PropertyAttributes* attributes,
                                InitializationFlag* init_flag,
                                VariableMode* variable_mode) {
+  DCHECK(!IsModuleContext());
   Isolate* isolate = GetIsolate();
   Handle<Context> context(this, isolate);