Ensure StyleSheetInsert-bootstrap.html doesn't spam willInsertBody IPCs

third_party/WebKit/PerformanceTests/CSS/StyleSheetInsert-bootstrap.html

Index: third_party/WebKit/PerformanceTests/CSS/StyleSheetInsert-bootstrap.html
diff --git a/third_party/WebKit/PerformanceTests/CSS/StyleSheetInsert-bootstrap.html b/third_party/WebKit/PerformanceTests/CSS/StyleSheetInsert-bootstrap.html
index 1b0987cf9d4482b741fc7e53894c828b690f20f8..201f7f2cf8f7442679851e73b58680a0d9fe4daa 100644
--- a/third_party/WebKit/PerformanceTests/CSS/StyleSheetInsert-bootstrap.html
+++ b/third_party/WebKit/PerformanceTests/CSS/StyleSheetInsert-bootstrap.html
@@ -19,10 +19,10 @@ PerfTestRunner.measureRunsPerSecond({
     description: "Measures performance of inserting a style elemenet ocntaining bootstrap's CSS into an iframe.",
     run:function() {
         var testDoc = document.getElementsByTagName("iframe")[0].contentDocument;
-        testDoc.documentElement.innerHTML = "";
         var style = testDoc.createElement("style");
         style.textContent = styleText;
         testDoc.documentElement.appendChild(style);
+        testDoc.documentElement.removeChild(testDoc.documentElement.lastElementChild);
     }
 });
 </script>