Fill in descriptions on relevant blink_perf tests

PerformanceTests/Parser/simple-url.html

Index: PerformanceTests/Parser/simple-url.html
diff --git a/PerformanceTests/Parser/simple-url.html b/PerformanceTests/Parser/simple-url.html
index 7fcde6b49a5c76ddca836e5a7c2b9e00716e017e..b75f8711e43a4fe79ca594afaf16a17edc2b7c33 100644
--- a/PerformanceTests/Parser/simple-url.html
+++ b/PerformanceTests/Parser/simple-url.html
@@ -3,10 +3,13 @@
 <script src="../resources/runner.js"></script>
 <script>
 var anchor = document.createElement("a");
-PerfTestRunner.measureRunsPerSecond({run:function() {
-    for (var x = 0; x < 200000; x++) {
-        anchor.href = "http://www.apple.com/"
+PerfTestRunner.measureRunsPerSecond({
+    description: "Measures performance of URL parsing by setting the href attribute on an <a> tag to a simple URL.",
+    run: function() {
+        for (var x = 0; x < 200000; x++) {
+            anchor.href = "http://www.apple.com/"
+        }
     }
-}});
+});
 </script>
 </body>