Add a performance test for removing OPTIONs from a SELECT element.

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-add.html b/third_party/WebKit/PerformanceTests/DOM/select-single-remove.html
similarity index 50%
copy from third_party/WebKit/PerformanceTests/DOM/select-single-add.html
copy to third_party/WebKit/PerformanceTests/DOM/select-single-remove.html
index 5d921d4e9776914fd4b04ffd79e3a08a02d734ee..5fb13d7679d7f56c8fe7c2d6d6d1e6b8a6c983ab 100644
--- a/third_party/WebKit/PerformanceTests/DOM/select-single-add.html
+++ b/third_party/WebKit/PerformanceTests/DOM/select-single-remove.html
@@ -5,18 +5,22 @@
 <script>
 var container = document.getElementById('container');
 var nodes = [];
-var childCount = 500;
+var childCount = 1000;
 for (var i = 0; i < childCount; ++i) {
-    nodes.push(document.createElement('option'));
-    nodes[i].selected = !!(i % 2);
+    var option = document.createElement('option');
+    option.textContent = i;
+    nodes.push(option);
 }
 
 PerfTestRunner.measureRunsPerSecond({
-    description: 'Measures performance of adding option elements to a single-selection select element.',
-    run: function() {
+    description: 'Measures performance of removing option elements from a single-selection select element.',
+
+    run: () => {
         for (var i = 0; i < childCount; ++i)
             container.appendChild(nodes[i]);
-        container.innerHTML = '';
+        container.offsetLeft;
+        for (var i = 0; i < childCount; ++i)
+            container.removeChild(nodes[i]);
     }
 });
 </script>