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

tracing/tracing/extras/importer/zip_importer.html

Index: tracing/tracing/extras/importer/zip_importer.html
diff --git a/tracing/tracing/extras/importer/zip_importer.html b/tracing/tracing/extras/importer/zip_importer.html
index dc2eda3929263cb4a8cda63c2b6cb16c5609c01f..a85150544b49d4829cc0733963ec0aa40e4ab0bb 100644
--- a/tracing/tracing/extras/importer/zip_importer.html
+++ b/tracing/tracing/extras/importer/zip_importer.html
@@ -19,8 +19,9 @@ found in the LICENSE file.
  */
 tr.exportTo('tr.e.importer', function() {
   function ZipImporter(model, eventData) {
-    if (eventData instanceof ArrayBuffer)
+    if (eventData instanceof ArrayBuffer) {
       eventData = new Uint8Array(eventData);
+    }
     this.model_ = model;
     this.eventData_ = eventData;
   }
@@ -31,12 +32,13 @@ tr.exportTo('tr.e.importer', function() {
    */
   ZipImporter.canImport = function(eventData) {
     var header;
-    if (eventData instanceof ArrayBuffer)
+    if (eventData instanceof ArrayBuffer) {
       header = new Uint8Array(eventData.slice(0, 2));
-    else if (typeof(eventData) === 'string' || eventData instanceof String)
+    } else if (typeof(eventData) === 'string' || eventData instanceof String) {
       header = [eventData.charCodeAt(0), eventData.charCodeAt(1)];
-    else
+    } else {
       return false;
+    }
     return header[0] === 'P'.charCodeAt(0) && header[1] === 'K'.charCodeAt(0);
   };
 
@@ -54,8 +56,9 @@ tr.exportTo('tr.e.importer', function() {
     extractSubtraces: function() {
       var zip = new JSZip(this.eventData_);
       var subtraces = [];
-      for (var idx in zip.files)
+      for (var idx in zip.files) {
         subtraces.push(zip.files[idx].asBinary());
+      }
       return subtraces;
     }
   };