Fix a bug in delete for lookup slots.

src/arm/codegen-arm.cc

 // Copyright 2010 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 5831 matching lines @@
 
     } else if (variable != NULL) {
       Slot* slot = variable->AsSlot();
       if (variable->is_global()) {
         LoadGlobal();
         frame_->EmitPush(Operand(variable->name()));
         frame_->InvokeBuiltin(Builtins::DELETE, CALL_JS, 2);
         frame_->EmitPush(r0);
 
       } else if (slot != NULL && slot->type() == Slot::LOOKUP) {
-        // lookup the context holding the named variable
+        // Delete from the context holding the named variable.
         frame_->EmitPush(cp);
         frame_->EmitPush(Operand(variable->name()));
-        frame_->CallRuntime(Runtime::kLookupContext, 2);
-        // r0: context
-        frame_->EmitPush(r0);
-        frame_->EmitPush(Operand(variable->name()));
-        frame_->InvokeBuiltin(Builtins::DELETE, CALL_JS, 2);
+        frame_->CallRuntime(Runtime::kDeleteContextSlot, 2);
         frame_->EmitPush(r0);
 
       } else {
         // Default: Result of deleting non-global, not dynamically
         // introduced variables is false.
         frame_->EmitPushRoot(Heap::kFalseValueRootIndex);
       }
 
     } else {
       // Default: Result of deleting expressions is true.
@@ skipping 1497 matching lines @@
                BinaryOpIC::GetName(runtime_operands_type_));
   return name_;
 }
 
 
 #undef __
 
 } }  // namespace v8::internal
 
 #endif  // V8_TARGET_ARCH_ARM