Improve handling of unary plus.

src/x64/full-codegen-x64.cc

Index: src/x64/full-codegen-x64.cc
diff --git a/src/x64/full-codegen-x64.cc b/src/x64/full-codegen-x64.cc
index 564c3def865d6b3535209e5bcf8fb32f19605a3c..8ca173b30fa18dcd9f735928a16091ac282573d2 100644
--- a/src/x64/full-codegen-x64.cc
+++ b/src/x64/full-codegen-x64.cc
@@ -3968,18 +3968,6 @@ void FullCodeGenerator::VisitUnaryOperation(UnaryOperation* expr) {
       break;
     }
 
-    case Token::ADD: {
-      Comment cmt(masm_, "[ UnaryOperation (ADD)");
-      VisitForAccumulatorValue(expr->expression());
-      Label no_conversion;
-      __ JumpIfSmi(result_register(), &no_conversion);
-      ToNumberStub convert_stub;
-      __ CallStub(&convert_stub);
-      __ bind(&no_conversion);
-      context()->Plug(result_register());
-      break;
-    }
-
     case Token::SUB:
       EmitUnaryOperation(expr, "[ UnaryOperation (SUB)");
       break;