Strip Interface class of most of its logic, make it all about Module exports

src/compiler/ast-graph-builder.cc

Index: src/compiler/ast-graph-builder.cc
diff --git a/src/compiler/ast-graph-builder.cc b/src/compiler/ast-graph-builder.cc
index 50216a766c074ec10c30872e6cf9f842288101ac..dfa295bbdbcb187786c1fd63b32d8f4a16470126 100644
--- a/src/compiler/ast-graph-builder.cc
+++ b/src/compiler/ast-graph-builder.cc
@@ -840,11 +840,6 @@ void AstGraphBuilder::VisitExportDeclaration(ExportDeclaration* decl) {
 void AstGraphBuilder::VisitModuleLiteral(ModuleLiteral* modl) { UNREACHABLE(); }
 
 
-void AstGraphBuilder::VisitModuleVariable(ModuleVariable* modl) {
-  UNREACHABLE();
-}
-
-
 void AstGraphBuilder::VisitModulePath(ModulePath* modl) { UNREACHABLE(); }