Fill in descriptions on relevant blink_perf tests

PerformanceTests/Animation/balls-transition-10-properties.html

Index: PerformanceTests/Animation/balls-transition-10-properties.html
diff --git a/PerformanceTests/Animation/balls-transition-10-properties.html b/PerformanceTests/Animation/balls-transition-10-properties.html
index 6a3e8c01d3eae6c3e9885e074d4d9b5ea8c86ae1..e688e5ed276d5d4db3ce880bb3c27e400eeb9126 100644
--- a/PerformanceTests/Animation/balls-transition-10-properties.html
+++ b/PerformanceTests/Animation/balls-transition-10-properties.html
@@ -70,7 +70,11 @@ var testRunning = true;
 var particles = [];
 
 window.onload = function () {
-    PerfTestRunner.prepareToMeasureValuesAsync({done: onCompletedRun, unit: 'fps'});
+    PerfTestRunner.prepareToMeasureValuesAsync({
+        description: 'Measures performance of CSS transition animation (animating on left and top, transition-property: [10 properties]).',

[rjwright, 2014/10/15 03:37:13]

This confused me, but I am not very familiar with the transitions API.

Maybe say

"Measures performance of CSS Transitions, with a transition on 10 properties but
only 'left' and 'top' changing."

Or

"Measures performance of CSS Transitions animating 'left' and 'top' with
transition-property: [10 properties]."

Or similar. Up to you.

+        done: onCompletedRun,
+        unit: 'fps'
+    });
 
     // Create the particles
     for (var i = 0; i < maxParticles; i++) {