message: add willReadFrequently on imread in js
diff: @@ -55,7 +55,7 @@ Module['imread'] = function(imageSource) {
  canvas = document.createElement('canvas');
  canvas.width = img.width;
  canvas.height = img.height;
  - ctx = canvas.getContext('2d');
  + ctx = canvas.getContext('2d', { willReadFrequently: true });
  ctx.drawImage(img, 0, 0, img.width, img.height);
  } else if (img instanceof HTMLCanvasElement) {
  canvas = img;
  