Fix loadFromJSON 404s breaking fabric (Image)

Prevent image 404s in Images from loadFromJSON from breaking everything
trying to get attributes of a source which is null, while passing it
upwards to allow dealing with images which failed to load outside of
Fabric.JS Issue #1079

src/shapes/image.class.js

@@ -252,7 +252,9 @@
      * @return {String} Source of an image
      */
     getSrc: function() {
-      return this.getElement().src || this.getElement()._src;
+      if(this.getElement()){
+        return this.getElement().src || this.getElement()._src;
+      }
     },
 
     /**
@@ -281,6 +283,10 @@
      */
     applyFilters: function(callback) {
 
+      if(!this._originalElement){
+        return;
+      }
+
       if (this.filters.length === 0) {
         this._element = this._originalElement;
         callback && callback();
@@ -330,13 +336,13 @@
      * @param {CanvasRenderingContext2D} ctx Context to render on
      */
     _render: function(ctx) {
-      ctx.drawImage(
-        this._element,
-        -this.width / 2,
-        -this.height / 2,
-        this.width,
-        this.height
-      );
+        this._element && ctx.drawImage(
+                           this._element,
+                           -this.width / 2,
+                           -this.height / 2,
+                           this.width,
+                           this.height
+                         );
     },
 
     /**
@@ -368,7 +374,9 @@
       options || (options = { });
       this.setOptions(options);
       this._setWidthHeight(options);
-      this._element.crossOrigin = this.crossOrigin;
+      if(this._element){
+        this._element.crossOrigin = this.crossOrigin;
+      }
     },
 
     /**
@@ -394,11 +402,11 @@
     _setWidthHeight: function(options) {
       this.width = 'width' in options
         ? options.width
-        : (this.getElement().width || 0);
+        : (this.getElement() ? this.getElement().width || 0 : 0);
 
       this.height = 'height' in options
         ? options.height
-        : (this.getElement().height || 0);
+        : (this.getElement() ? this.getElement().height || 0 : 0);
     },
 
     /**

src/util/dom_misc.js

@@ -68,7 +68,7 @@
    * @param {String} className Class to add to an element
    */
   function addClass(element, className) {
-    if ((' ' + element.className + ' ').indexOf(' ' + className + ' ') === -1) {
+    if (element && (' ' + element.className + ' ').indexOf(' ' + className + ' ') === -1) {
       element.className += (element.className ? ' ' : '') + className;
     }
   }