hasDescendantWithBlendMode should not be propagated outside the current stacking context.

PerformanceTests/Blending/resources/framerate.js

Index: PerformanceTests/Blending/resources/framerate.js
diff --git a/PerformanceTests/Animation/resources/framerate.js b/PerformanceTests/Blending/resources/framerate.js
similarity index 77%
copy from PerformanceTests/Animation/resources/framerate.js
copy to PerformanceTests/Blending/resources/framerate.js
index 2b3d0c03c59ee2e0ea931f9e07ecfd5e1f1f1397..6871eba7df0ff9d1123ef0e928cd03c3c370d843 100644
--- a/PerformanceTests/Animation/resources/framerate.js
+++ b/PerformanceTests/Blending/resources/framerate.js
@@ -4,6 +4,7 @@ var framesPerTimerReading = 10;
 var frameCount = 0;
 var startTime;
 var trackingFrameRate = false;
+var currentTest;
 
 function trackFrameRate(currTime)
 {
@@ -13,20 +14,25 @@ function trackFrameRate(currTime)
         startTime = currTime;
     }
 
+    if (currentTest && currentTest.run)
+        currentTest.run();
+
     if (trackingFrameRate)
         requestAnimationFrame(trackFrameRate);
 }
 
-window.startTrackingFrameRate = function() {
+window.startTrackingFrameRate = function(test) {
     if (trackingFrameRate)
         return;
     trackingFrameRate = true;
+    currentTest = test;
     startTime = performance.now();
     trackFrameRate();
 };
 
 window.stopTrackingFrameRate = function() {
     trackingFrameRate = false;
+    currentTest = undefined;
 };
 
 })();