Update canvas loadFromJSON to restore includeProperties (#2921)

added test also.

src/mixins/canvas_serialization.mixin.js

@@ -46,7 +46,7 @@ fabric.util.object.extend(fabric.StaticCanvas.prototype, /** @lends fabric.Stati
     // serialize if it wasn't already
     var serialized = (typeof json === 'string')
       ? JSON.parse(json)
-      : json;
+      : fabric.util.object.clone(json);
 
     this.clear();
 
@@ -54,7 +54,19 @@ fabric.util.object.extend(fabric.StaticCanvas.prototype, /** @lends fabric.Stati
     this._enlivenObjects(serialized.objects, function () {
       _this._setBgOverlay(serialized, callback);
     }, reviver);
-
+    // remove parts i cannot set as options
+    delete serialized.objects;
+    delete serialized.backgroundImage;
+    delete serialized.overlayImage;
+    delete serialized.background;
+    delete serialized.overlay;
+    // this._initOptions does too many things to just
+    // call it. Normally loading an Object from JSON
+    // create the Object instance. Here the Canvas is
+    // already an instance and we are just loading things over it
+    for (var prop in serialized) {
+      this[prop] = serialized[prop];
+    }
     return this;
   },
 

test/unit/canvas_static.js

@@ -766,6 +766,19 @@
     });
   });
 
+  test('loadFromJSON with custom properties on Canvas', function() {
+    var serialized = JSON.parse(PATH_JSON);
+    serialized.controlsAboveOverlay = true;
+    serialized.preserveObjectStacking = true;
+    canvas.loadFromJSON(serialized, function() {
+      ok(!canvas.isEmpty(), 'canvas is not empty');
+      equal(fabric.Canvas.prototype.controlsAboveOverlay, false);
+      equal(fabric.Canvas.prototype.preserveObjectStacking, false);
+    });
+    equal(canvas.controlsAboveOverlay, true);
+    equal(canvas.preserveObjectStacking, true);
+  });
+
   test('loadFromJSON custom properties', function() {
     var rect = new fabric.Rect({ width: 10, height: 20 });
     rect.padding = 123;