Access current frame counter carefully and remove m_cachedSampleFrame.

LayoutTests/webaudio/scriptprocessornode.html

Index: LayoutTests/webaudio/scriptprocessornode.html
diff --git a/LayoutTests/webaudio/scriptprocessornode.html b/LayoutTests/webaudio/scriptprocessornode.html
index c65ddc6fa62754c66f1640064280e7d2c6bea9f2..4883400c986f766a763d60405166abca9403cfec 100644
--- a/LayoutTests/webaudio/scriptprocessornode.html
+++ b/LayoutTests/webaudio/scriptprocessornode.html
@@ -46,18 +46,10 @@ function processAudioData(event) {
     var allowedTimeGap = 0.0000001;
 
     // There may be a little time gap which is from different thread operation
-    // between currentTime when main thread fires onaudioprocess() and currenTime when read in JS
-    // since currentTime is continuously increasing on audio thread.  And caching of the currentTime
-    // can cause playbackTime to be one block behind. So allow for that.
+    // between currentTime when main thread fires onaudioprocess() and currentTime when read in JS
+    // since currentTime is continuously increasing on audio thread.
 
-    var closeEnough = Math.abs(playbackTime - expectedTime) <= allowedTimeGap;
-    closeEnough = closeEnough || (Math.abs(playbackTime - (expectedTime - 128 / context.sampleRate)) <= allowedTimeGap);
-
-    if (!closeEnough) {
-        testFailed("playbackTime should be within " + allowedTimeGap + " of either "
-                   + expectedTime + " or " + (expectedTime - 128 / context.sampleRate)
-                   + ". Was " + playbackTime);
-    }
+    shouldBeCloseTo("playbackTime", expectedTime, allowedTimeGap, true);
 
     buffer = event.outputBuffer;
     if (buffer.numberOfChannels != outputChannels)