Move 'use strict' to file level

Change-Id: I1f0dae4aa168e77c112bcd3688c98b84e4ce5f36
diff --git a/dev/js/src/match/treehierarchy.js b/dev/js/src/match/treehierarchy.js
index e54ef29..5273089 100644
--- a/dev/js/src/match/treehierarchy.js
+++ b/dev/js/src/match/treehierarchy.js
@@ -4,8 +4,9 @@
  *
  * This should be lazy loaded!
  */
+"use strict";
+
 define(['lib/dagre'], function (dagre) {
-  "use strict";
 
   const d = document;
   const svgNS = "http://www.w3.org/2000/svg";