added performance test suite with two sample performance tests

tests/js/performanceTests.js

@@ -0,0 +1,74 @@
+Test.prototype.tests = {
+    'PERFORMANCE - draw rect vs image from image data': function(containerId) {
+        var stage = new Kinetic.Stage({
+            container: containerId,
+            width: 578,
+            height: 200
+        });
+        var layer = new Kinetic.Layer();
+        stage.add(layer);
+
+        var canvas = layer.getCanvas();
+        var context = layer.getContext();
+
+        startTimer();
+        for(var n = 0; n < 10000; n++) {
+            context.fillStyle = 'blue';
+            context.lineWidth = 6;
+            context.strokeStyle = 'red';
+            context.fillRect(10, 10, 100, 100);
+            context.strokeRect(10, 10, 100, 100);
+        }
+        endTimer('draw 10,000 rects with canvas API');
+
+        startTimer();
+        var imageData = context.getImageData(7, 7, 106, 106);
+        endTimer('create image data');
+
+        layer.clear();
+
+        startTimer();
+        for(var n = 0; n < 10000; n++) {
+            context.putImageData(imageData, 7, 7);
+        }
+        endTimer('draw 10,000 images with image object from image data');
+
+    },
+    'PERFORMANCE - draw rect vs image from data url': function(containerId) {
+        var stage = new Kinetic.Stage({
+            container: containerId,
+            width: 578,
+            height: 200
+        });
+        var layer = new Kinetic.Layer();
+        stage.add(layer);
+
+        var canvas = layer.getCanvas();
+        var context = layer.getContext();
+
+        startTimer();
+        for(var n = 0; n < 10000; n++) {
+            context.fillStyle = 'blue';
+            context.lineWidth = 6;
+            context.strokeStyle = 'red';
+            context.fillRect(10, 10, 100, 100);
+            context.strokeRect(10, 10, 100, 100);
+        }
+        endTimer('draw 10,000 rects with canvas API');
+
+        startTimer();
+        var url = canvas.toDataURL();
+        endTimer('create data url');
+
+        var imageObj = new Image();
+        imageObj.src = url;
+
+        layer.clear();
+
+        startTimer();
+        for(var n = 0; n < 10000; n++) {
+            context.drawImage(imageObj, 7, 7, 106, 106, 10, 10, 106, 106);
+        }
+        endTimer('draw 10,000 images with image object from data url');
+    }
+};