Clean up ImageBitmapRenderingContext tests 
diff --git a/imagebitmap-renderingcontext/transferFromImageBitmap-detached.html b/imagebitmap-renderingcontext/transferFromImageBitmap-detached.html index 2c547ee..c0ae841 100644 --- a/imagebitmap-renderingcontext/transferFromImageBitmap-detached.html +++ b/imagebitmap-renderingcontext/transferFromImageBitmap-detached.html 
@@ -28,7 +28,7 @@  var ctx = srcCanvas.getContext('2d');  ctx.fillStyle = 'rgba(0, 255, 0, 0.5)';  ctx.fillRect(0, 0, width, height); - createImageBitmap(srcCanvas).then(testException); + return createImageBitmap(srcCanvas).then(testException);  }, "Test transferFromImageBitmap(image) with a detached image should throw InvalidStateError");    </script>