[crankshaft] Remove the useless HAllocateBlockContext instruction.

src/crankshaft/ppc/lithium-ppc.cc

 // Copyright 2014 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/crankshaft/ppc/lithium-ppc.h"
 
 #include <sstream>
 
 #include "src/crankshaft/hydrogen-osr.h"
 #include "src/crankshaft/lithium-inl.h"
@@ skipping 2535 matching lines @@
   LInstruction* result = DefineSameAsFirst(load);
   return AssignPointerMap(result);
 }
 
 
 LInstruction* LChunkBuilder::DoStoreFrameContext(HStoreFrameContext* instr) {
   LOperand* context = UseRegisterAtStart(instr->context());
   return new (zone()) LStoreFrameContext(context);
 }
 
-
-LInstruction* LChunkBuilder::DoAllocateBlockContext(
-    HAllocateBlockContext* instr) {
-  LOperand* context = UseFixed(instr->context(), cp);
-  LOperand* function = UseRegisterAtStart(instr->function());
-  LAllocateBlockContext* result =
-      new (zone()) LAllocateBlockContext(context, function);
-  return MarkAsCall(DefineFixed(result, cp), instr);
-}
 }  // namespace internal
 }  // namespace v8