Adopt strict mode throughout the codebase

src/html/HtmlExactSpecFilter.js

@@ -1,4 +1,6 @@
 jasmineRequire.HtmlExactSpecFilter = function() {
+  'use strict';
+
   /**
    * Spec filter for use with {@link HtmlReporter}
    *

src/html/HtmlReporter.js

@@ -1,4 +1,6 @@
 jasmineRequire.HtmlReporter = function(j$) {
+  'use strict';
+
   function ResultsStateBuilder() {
     this.topResults = new j$.private.ResultsNode({}, '', null);
     this.currentParent = this.topResults;

src/html/HtmlSpecFilter.js

@@ -1,4 +1,6 @@
 jasmineRequire.HtmlSpecFilter = function() {
+  'use strict';
+
   /**
    * @name HtmlSpecFilter
    * @classdesc Legacy HTML spec filter, for backward compatibility

src/html/QueryString.js

@@ -1,4 +1,6 @@
 jasmineRequire.QueryString = function() {
+  'use strict';
+
   /**
    * Reads and manipulates the query string.
    * @since 2.0.0

src/html/ResultsNode.js

@@ -1,4 +1,6 @@
 jasmineRequire.ResultsNode = function() {
+  'use strict';
+
   function ResultsNode(result, type, parent) {
     this.result = result;
     this.type = type;