[Interpreter] Add support for Load / Store to Lookup slots.

src/interpreter/bytecode-generator.cc

 // Copyright 2015 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/interpreter/bytecode-generator.h"
 
 #include "src/ast/scopes.h"
 #include "src/compiler.h"
 #include "src/interpreter/control-flow-builders.h"
 #include "src/objects.h"
@@ skipping 1326 matching lines @@
               ->LoadContextSlot(context_reg, Context::PREVIOUS_INDEX)
               .StoreAccumulatorInRegister(context_reg);
         }
       }
       builder()->LoadContextSlot(context_reg, variable->index());
       execution_result()->SetResultInAccumulator();
       // TODO(rmcilroy): Perform check for uninitialized legacy const, const and
       // let variables.
       break;
     }
-    case VariableLocation::LOOKUP:
-      UNIMPLEMENTED();
+    case VariableLocation::LOOKUP: {
+      builder()->LoadLookupSlot(variable->name(), typeof_mode);
+      execution_result()->SetResultInAccumulator();
+      break;
+    }
   }
 }
 
 
 void BytecodeGenerator::VisitVariableLoadForAccumulatorValue(
     Variable* variable, FeedbackVectorSlot slot, TypeofMode typeof_mode) {
   AccumulatorResultScope accumulator_result(this);
   VisitVariableLoad(variable, slot, typeof_mode);
 }
 
@@ skipping 55 matching lines @@
         for (int i = 0; i < depth; ++i) {
           builder()
               ->LoadContextSlot(context_reg, Context::PREVIOUS_INDEX)
               .StoreAccumulatorInRegister(context_reg);
         }
         builder()->LoadAccumulatorWithRegister(value_temp);
       }
       builder()->StoreContextSlot(context_reg, variable->index());
       break;
     }
-    case VariableLocation::LOOKUP:
-      UNIMPLEMENTED();
+    case VariableLocation::LOOKUP: {
+      builder()->StoreLookupSlot(variable->name(), language_mode());
+      break;
+    }
   }
 }
 
 
 void BytecodeGenerator::VisitAssignment(Assignment* expr) {
   DCHECK(expr->target()->IsValidReferenceExpression());
   Register object, key;
   size_t name_index = kMaxUInt32;
 
   // Left-hand side can only be a property, a global or a variable slot.
@@ skipping 801 matching lines @@
 }
 
 
 int BytecodeGenerator::feedback_index(FeedbackVectorSlot slot) const {
   return info()->feedback_vector()->GetIndex(slot);
 }
 
 }  // namespace interpreter
 }  // namespace internal
 }  // namespace v8