Remove obsolete instruction HOuterContext.

src/x64/lithium-x64.cc

Index: src/x64/lithium-x64.cc
diff --git a/src/x64/lithium-x64.cc b/src/x64/lithium-x64.cc
index 493650328d9a5058cad59e108276ca276403ea05..76c831572309f3fc1d7d21671ba7387b66c9bcc1 100644
--- a/src/x64/lithium-x64.cc
+++ b/src/x64/lithium-x64.cc
@@ -1049,12 +1049,6 @@ LInstruction* LChunkBuilder::DoContext(HContext* instr) {
 }
 
 
-LInstruction* LChunkBuilder::DoOuterContext(HOuterContext* instr) {
-  LOperand* context = UseRegisterAtStart(instr->value());
-  return DefineAsRegister(new(zone()) LOuterContext(context));
-}
-
-
 LInstruction* LChunkBuilder::DoDeclareGlobals(HDeclareGlobals* instr) {
   LOperand* context = UseFixed(instr->context(), rsi);
   return MarkAsCall(new(zone()) LDeclareGlobals(context), instr);