Improve handling of unary plus.

src/mips/full-codegen-mips.cc

Index: src/mips/full-codegen-mips.cc
diff --git a/src/mips/full-codegen-mips.cc b/src/mips/full-codegen-mips.cc
index 8e2d5abbeda823bb30f5ae9c7a19290339b452d8..bc0d85543b8b96b43da89f11ae28237d3291ad44 100644
--- a/src/mips/full-codegen-mips.cc
+++ b/src/mips/full-codegen-mips.cc
@@ -3995,19 +3995,6 @@ 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);
-      __ mov(a0, result_register());
-      ToNumberStub convert_stub;
-      __ CallStub(&convert_stub);
-      __ bind(&no_conversion);
-      context()->Plug(result_register());
-      break;
-    }
-
     case Token::SUB:
       EmitUnaryOperation(expr, "[ UnaryOperation (SUB)");
       break;