Fill in descriptions on relevant blink_perf tests

PerformanceTests/Parser/textarea-parsing.html

Index: PerformanceTests/Parser/textarea-parsing.html
diff --git a/PerformanceTests/Parser/textarea-parsing.html b/PerformanceTests/Parser/textarea-parsing.html
index ce534ce5e608fbc212d44f21d6156d6789e3e814..f74583f7a8bf60ac004d46ed0f832db4ee361498 100644
--- a/PerformanceTests/Parser/textarea-parsing.html
+++ b/PerformanceTests/Parser/textarea-parsing.html
@@ -20,8 +20,11 @@ for (var i = 0; i < 1000; ++i) {
 htmlText += "</textarea>"
 
 var container = document.getElementById('container');
-PerfTestRunner.measureRunsPerSecond({run: function() {
-    container.innerHTML = htmlText;
-}});
+PerfTestRunner.measureRunsPerSecond({
+    description: "Measures performance of parsing within a <textarea> tag.",
+    run: function() {
+        container.innerHTML = htmlText;
+    }
+});
 </script>
 </body>