image element, minor

* image.toJson -> image.toJSON.
* remove unused 'fill' and 'operator' properties.

area.js

@@ -630,7 +630,6 @@ var DrawingArea = new Lang.Class({
                 color: this.currentColor,
                 eraser: eraser,
                 image: this.currentImage,
-                operator: this.currentOperator,
                 points: []
             });
         } else {

elements.js

@@ -767,19 +767,13 @@ const ImageElement = new Lang.Class({
     Name: 'DrawOnYourScreenImageElement',
     Extends: _DrawingElement,
     
-    _init: function(params) {
-        params.fill = false;
-        this.parent(params);
-    },
-    
     toJSON: function() {
         return {
             shape: this.shape,
             color: this.color,
-            fill: this.fill,
             eraser: this.eraser,
             transformations: this.transformations,
-            image: this.image.toJson(),
+            image: this.image,
             preserveAspectRatio: this.preserveAspectRatio,
             points: this.points.map((point) => [Math.round(point[0]*100)/100, Math.round(point[1]*100)/100])
         };

files.js

@@ -97,7 +97,7 @@ var Image = new Lang.Class({
         return this.displayName;
     },
     
-    toJson: function() {
+    toJSON: function() {
         return {
             displayName: this.displayName,
             contentType: this.contentType,