allow html Forms in plugins / improve export demo

Change-Id: I62e6e1de41b2e69fd3dea2afec0cf6d213493eac
diff --git a/dev/js/spec/pluginSpec.js b/dev/js/spec/pluginSpec.js
index 41589ec..570f3f4 100644
--- a/dev/js/spec/pluginSpec.js
+++ b/dev/js/spec/pluginSpec.js
@@ -174,7 +174,7 @@
 
       var iframe = we.firstChild;
       expect(iframe.tagName).toEqual("IFRAME");
-      expect(iframe.getAttribute("sandbox")).toEqual("allow-scripts");
+      expect(iframe.getAttribute("sandbox")).toEqual("allow-scripts allow-forms");
       expect(iframe.getAttribute("src")).toEqual("https://example");
       expect(iframe.getAttribute("name")).toEqual("56");
 
diff --git a/dev/js/src/plugin/service.js b/dev/js/src/plugin/service.js
index a02e945..c1d29e8 100644
--- a/dev/js/src/plugin/service.js
+++ b/dev/js/src/plugin/service.js
@@ -34,7 +34,8 @@
       let e = document.createElement('iframe');
       e.setAttribute('allowTransparency',"true");
       e.setAttribute('frameborder', 0);
-      e.setAttribute('sandbox','allow-scripts');
+      // Allow forms in Plugins
+      e.setAttribute('sandbox','allow-scripts allow-forms');
       e.style.height = '0px';
       e.setAttribute('name', this.id);
       e.setAttribute('src', this.src);