Delegate a click from flow-component-renderer to the first child (#4270)

Do it ONLY if the target is the flow-component-renderer element itself.

Fixes grid#122

flow-data/src/main/resources/META-INF/resources/frontend/flow-component-renderer.html

@@ -19,6 +19,17 @@
       ]
     }
 
+    ready(){
+        super.ready();
+        this.addEventListener("click", function(event){
+            if (this.firstChild && 
+                    typeof this.firstChild.click === "function" && 
+                        event.target === this ){
+                this.firstChild.click();
+            }
+        });
+    }
+
     _asyncAttachRenderedComponentIfAble() {
       this._debouncer = Polymer.Debouncer.debounce(
         this._debouncer,