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

tracing/tracing/ui/analysis/multi_async_slice_sub_view.html

Index: tracing/tracing/ui/analysis/multi_async_slice_sub_view.html
diff --git a/tracing/tracing/ui/analysis/multi_async_slice_sub_view.html b/tracing/tracing/ui/analysis/multi_async_slice_sub_view.html
index d97043e9ef392cafae0398a4c8668ff457651851..e172e1fc121ef5f9e02e7556cd1bc49755888048 100644
--- a/tracing/tracing/ui/analysis/multi_async_slice_sub_view.html
+++ b/tracing/tracing/ui/analysis/multi_async_slice_sub_view.html
@@ -55,18 +55,17 @@ Polymer({
   },
 
   get relatedEventsToHighlight() {
-    if (!this.$.content.selection)
-      return undefined;
+    if (!this.$.content.selection) return undefined;
+
     var selection = new tr.model.EventSet();
     this.$.content.selection.forEach(function(asyncEvent) {
-      if (!asyncEvent.associatedEvents)
-        return;
+      if (!asyncEvent.associatedEvents) return;
+
       asyncEvent.associatedEvents.forEach(function(event) {
         selection.push(event);
       });
     });
-    if (selection.length)
-      return selection;
+    if (selection.length) return selection;
     return undefined;
   }
 });