Fix two x64 code generation bugs introduced by const context slot code.

src/x64/lithium-codegen-x64.cc

 // Copyright 2011 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 2056 matching lines @@
   Register context = ToRegister(instr->context());
   Register result = ToRegister(instr->result());
   __ movq(result, ContextOperand(context, instr->slot_index()));
   if (instr->hydrogen()->RequiresHoleCheck()) {
     __ CompareRoot(result, Heap::kTheHoleValueRootIndex);
     if (instr->hydrogen()->DeoptimizesOnHole()) {
       DeoptimizeIf(equal, instr->environment());
     } else {
       Label is_not_hole;
       __ j(not_equal, &is_not_hole, Label::kNear);
-      __ movq(result, factory()->undefined_value(), RelocInfo::NONE);
+      __ LoadRoot(result, Heap::kUndefinedValueRootIndex);
       __ bind(&is_not_hole);
     }
   }
 }
 
 
 void LCodeGen::DoStoreContextSlot(LStoreContextSlot* instr) {
   Register context = ToRegister(instr->context());
   Register value = ToRegister(instr->value());
 
   Operand target = ContextOperand(context, instr->slot_index());
 
   Label skip_assignment;
   if (instr->hydrogen()->RequiresHoleCheck()) {
     __ CompareRoot(target, Heap::kTheHoleValueRootIndex);
     if (instr->hydrogen()->DeoptimizesOnHole()) {
       DeoptimizeIf(equal, instr->environment());
     } else {
-      __ j(not_equal, &skip_assignment, Label::kNear);
+      __ j(not_equal, &skip_assignment);
     }
   }
   __ movq(target, value);
 
   if (instr->hydrogen()->NeedsWriteBarrier()) {
     HType type = instr->hydrogen()->value()->type();
     SmiCheck check_needed =
         type.IsHeapObject() ? OMIT_SMI_CHECK : INLINE_SMI_CHECK;
     int offset = Context::SlotOffset(instr->slot_index());
     Register scratch = ToRegister(instr->TempAt(0));
@@ skipping 2227 matching lines @@
   RegisterEnvironmentForDeoptimization(environment, Safepoint::kNoLazyDeopt);
   ASSERT(osr_pc_offset_ == -1);
   osr_pc_offset_ = masm()->pc_offset();
 }
 
 #undef __
 
 } }  // namespace v8::internal
 
 #endif  // V8_TARGET_ARCH_X64