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

src/ast/variables.cc

 // Copyright 2011 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "src/ast/variables.h"
 
 #include "src/ast/ast.h"
 #include "src/ast/scopes.h"
 #include "src/globals.h"
 
 namespace v8 {
 namespace internal {
 
 // ----------------------------------------------------------------------------
 // Implementation Variable.
 
 const char* Variable::Mode2String(VariableMode mode) {
   switch (mode) {
     case VAR: return "VAR";
     case CONST_LEGACY: return "CONST_LEGACY";
     case LET: return "LET";
     case CONST: return "CONST";
-    case IMPORT: return "IMPORT";
     case DYNAMIC: return "DYNAMIC";
     case DYNAMIC_GLOBAL: return "DYNAMIC_GLOBAL";
     case DYNAMIC_LOCAL: return "DYNAMIC_LOCAL";
     case TEMPORARY: return "TEMPORARY";
   }
   UNREACHABLE();
   return NULL;
 }
 
 Variable::Variable(Scope* scope, const AstRawString* name, VariableMode mode,
@@ skipping 35 matching lines @@
 
 int Variable::CompareIndex(Variable* const* v, Variable* const* w) {
   int x = (*v)->index();
   int y = (*w)->index();
   // Consider sorting them according to type as well?
   return x - y;
 }
 
 }  // namespace internal
 }  // namespace v8