[interpreter] Don't keep postfix result if only visited for effect

test/cctest/interpreter/bytecode_expectations/BasicLoops.golden

Index: test/cctest/interpreter/bytecode_expectations/BasicLoops.golden
diff --git a/test/cctest/interpreter/bytecode_expectations/BasicLoops.golden b/test/cctest/interpreter/bytecode_expectations/BasicLoops.golden
index a87b10d89989c1b017bfb9355ea0336232e726c1..7c71644afac3174d396d26621d969fc24f4582b5 100644
--- a/test/cctest/interpreter/bytecode_expectations/BasicLoops.golden
+++ b/test/cctest/interpreter/bytecode_expectations/BasicLoops.golden
@@ -679,15 +679,15 @@ snippet: "
     }
   }
 "
-frame size: 7
+frame size: 6
 parameter count: 1
-bytecode array length: 118
+bytecode array length: 116
 bytecodes: [
   /*   30 E> */ B(StackCheck),
   /*   42 S> */ B(LdaZero),
                 B(Star), R(1),
   /*   52 S> */ B(Ldar), R(1),
-                B(JumpIfToBooleanFalse), U8(110),
+                B(JumpIfToBooleanFalse), U8(108),
   /*   45 E> */ B(StackCheck),
                 B(LdaConstant), U8(0),
                 B(Star), R(4),
@@ -714,24 +714,23 @@ bytecodes: [
                 B(JumpIfToBooleanFalse), U8(8),
   /*  113 S> */ B(PopContext), R(3),
                 B(PopContext), R(3),
-                B(Jump), U8(42),
+                B(Jump), U8(40),
   /*  126 S> */ B(LdaContextSlot), R(context), U8(4),
                 B(JumpIfNotHole), U8(11),
                 B(LdaConstant), U8(3),
                 B(Star), R(4),
                 B(CallRuntime), U16(Runtime::kThrowReferenceError), R(4), U8(1),
-                B(ToNumber), R(4),
                 B(Inc),
-                B(Star), R(5),
+                B(Star), R(4),
   /*  127 E> */ B(LdaContextSlot), R(context), U8(4),
                 B(JumpIfNotHole), U8(11),
                 B(LdaConstant), U8(3),
-                B(Star), R(6),
-                B(CallRuntime), U16(Runtime::kThrowReferenceError), R(6), U8(1),
-                B(Ldar), R(5),
+                B(Star), R(5),
+                B(CallRuntime), U16(Runtime::kThrowReferenceError), R(5), U8(1),
+                B(Ldar), R(4),
                 B(StaContextSlot), R(context), U8(4),
                 B(PopContext), R(3),
-                B(Jump), U8(-110),
+                B(Jump), U8(-108),
                 B(LdaUndefined),
   /*  137 S> */ B(Return),
 ]