Fix a wrong test landed in r400392.

third_party/WebKit/PerformanceTests/DOM/select-single-remove.html

Index: third_party/WebKit/PerformanceTests/DOM/select-single-remove.html
diff --git a/third_party/WebKit/PerformanceTests/DOM/select-single-remove.html b/third_party/WebKit/PerformanceTests/DOM/select-single-remove.html
index 5fb13d7679d7f56c8fe7c2d6d6d1e6b8a6c983ab..158c62dca9cb3dc7c3d6968a1eeff6c25a1d9bb6 100644
--- a/third_party/WebKit/PerformanceTests/DOM/select-single-remove.html
+++ b/third_party/WebKit/PerformanceTests/DOM/select-single-remove.html
@@ -16,8 +16,10 @@ PerfTestRunner.measureRunsPerSecond({
     description: 'Measures performance of removing option elements from a single-selection select element.',
 
     run: () => {
-        for (var i = 0; i < childCount; ++i)
+        for (var i = 0; i < childCount; ++i) {
+            nodes[i].selected = false;
             container.appendChild(nodes[i]);
+        }
         container.offsetLeft;
         for (var i = 0; i < childCount; ++i)
             container.removeChild(nodes[i]);