Merge pull request #1287 from nockawa/master

 	Fixing cachedGroup to be render again when primitive just got disposed

src/Canvas2d/babylon.group2d.ts

@@ -525,6 +525,10 @@
             }
         }
 
+        public _setCacheGroupDirty() {
+            this._cacheGroupDirty = true;
+        }
+
         private _updateTransparentData() {
             this.owner._addUpdateTransparentDataCount(1);
 

src/Canvas2d/babylon.renderablePrim2d.ts

@@ -403,6 +403,10 @@
                 return false;
             }
 
+            if (this.renderGroup) {
+                this.renderGroup._setCacheGroupDirty();
+            }
+
             if (this._transparentPrimitiveInfo) {
                 this.renderGroup._renderableData.removeTransparentPrimitiveInfo(this._transparentPrimitiveInfo);
                 this._transparentPrimitiveInfo = null;