[modules] Introduce new VariableLocation for module imports/exports.

src/ast/scopes.h

Index: src/ast/scopes.h
diff --git a/src/ast/scopes.h b/src/ast/scopes.h
index 304b877bfacdf803319401502cea2d43778da90c..bcf61fe9ba2e146dbb0b8811ff73c4bc6fe9b0cb 100644
--- a/src/ast/scopes.h
+++ b/src/ast/scopes.h
@@ -578,6 +578,9 @@ class Scope: public ZoneObject {
   // a context) or declaring temporaries.
   Scope* ClosureScope();
 
+  // Find the module scope if there is one.
+  Scope* ModuleScope();
+
   // Find the first (non-arrow) function or script scope.  This is where
   // 'this' is bound, and what determines the function kind.
   Scope* ReceiverScope();
@@ -826,6 +829,9 @@ class Scope: public ZoneObject {
   void AllocateVariablesRecursively(AstValueFactory* ast_value_factory);
   void AllocateParameter(Variable* var, int index);
   void AllocateReceiver();
+  // Set MODULE as VariableLocation for all variables that will live in some
+  // module's export table.
+  void AllocateModuleVariables();
 
   // Resolve and fill in the allocation information for all variables
   // in this scopes. Must be called *after* all scopes have been