[ESLint] Fix violations when enabling curly rule in eslint.

tracing/tracing/ui/base/utils.html

Index: tracing/tracing/ui/base/utils.html
diff --git a/tracing/tracing/ui/base/utils.html b/tracing/tracing/ui/base/utils.html
index 3ebe8254d10382f120e3b49de68ca443000db9ef..6c1888e1320f6a9521de963e53861485bcd7b88c 100644
--- a/tracing/tracing/ui/base/utils.html
+++ b/tracing/tracing/ui/base/utils.html
@@ -15,8 +15,9 @@ tr.exportTo('tr.ui.b', function() {
   function instantiateTemplate(selector, doc) {
     doc = doc || document;
     var el = Polymer.dom(doc).querySelector(selector);
-    if (!el)
+    if (!el) {
       throw new Error('Element not found');
+    }
     return doc.importNode(el.content, true);
 //    return el.createInstance();
   }