Merge pull request #3044 from gberaudo/api_image_style_constructor_properties

Mark Image style constructor properties `@api`

src/ol/style/imagestyle.js

@@ -70,6 +70,7 @@ ol.style.Image = function(options) {
 
 /**
  * @return {number} Opacity.
+ * @api
  */
 ol.style.Image.prototype.getOpacity = function() {
   return this.opacity_;
@@ -78,6 +79,7 @@ ol.style.Image.prototype.getOpacity = function() {
 
 /**
  * @return {boolean} Rotate with map.
+ * @api
  */
 ol.style.Image.prototype.getRotateWithView = function() {
   return this.rotateWithView_;
@@ -104,6 +106,7 @@ ol.style.Image.prototype.getScale = function() {
 
 /**
  * @return {boolean} Snap to pixel?
+ * @api
  */
 ol.style.Image.prototype.getSnapToPixel = function() {
   return this.snapToPixel_;