Re-introduce ImportDeclaration to the parser

src/contexts.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/v8.h"
 
 #include "src/bootstrapper.h"
 #include "src/debug.h"
 #include "src/scopeinfo.h"
 
@@ skipping 155 matching lines @@
       *binding_flags = (init_flag == kNeedsInitialization)
                            ? IMMUTABLE_CHECK_INITIALIZED
                            : IMMUTABLE_IS_INITIALIZED;
       break;
     case CONST:
       *attributes = READ_ONLY;
       *binding_flags = (init_flag == kNeedsInitialization)
                            ? IMMUTABLE_CHECK_INITIALIZED_HARMONY
                            : IMMUTABLE_IS_INITIALIZED_HARMONY;
       break;
+    case IMPORT:
+      // TODO(ES6)
+      UNREACHABLE();
+      break;
     case DYNAMIC:
     case DYNAMIC_GLOBAL:
     case DYNAMIC_LOCAL:
     case TEMPORARY:
       // Note: Fixed context slots are statically allocated by the compiler.
       // Statically allocated variables always have a statically known mode,
       // which is the mode with which they were declared when added to the
       // scope. Thus, the DYNAMIC mode (which corresponds to dynamically
       // declared variables that were introduced through declaration nodes)
       // must not appear here.
@@ skipping 299 matching lines @@
 bool Context::IsBootstrappingOrGlobalObject(Isolate* isolate, Object* object) {
   // During bootstrapping we allow all objects to pass as global
   // objects. This is necessary to fix circular dependencies.
   return isolate->heap()->gc_state() != Heap::NOT_IN_GC ||
       isolate->bootstrapper()->IsActive() ||
       object->IsGlobalObject();
 }
 #endif
 
 } }  // namespace v8::internal