diff --git a/toolkit/devtools/shared/test/browser_tableWidget_basic.js b/toolkit/devtools/shared/test/browser_tableWidget_basic.js
index de71540078..11446e884f 100644
--- a/toolkit/devtools/shared/test/browser_tableWidget_basic.js
+++ b/toolkit/devtools/shared/test/browser_tableWidget_basic.js
@@ -125,8 +125,8 @@ function populateTable() {
  * Test if the nodes are inserted correctly in the table.
  */
 function testTreeItemInsertedCorrectly() {
-  is(table.tbody.children.length, 4*2 /* double because splitters */,
-     "4 columns exist");
+  // double because splitters
+  is(table.tbody.children.length, 4 * 2, "4 columns exist");
 
   // Test firstColumn option and check if the nodes are inserted correctly
   is(table.tbody.children[0].firstChild.children.length, 9 + 1 /* header */,
@@ -135,7 +135,8 @@ function testTreeItemInsertedCorrectly() {
      "Correct column header value");
 
   for (let i = 1; i < 4; i++) {
-    is(table.tbody.children[i * 2].firstChild.children.length, 9 + 1 /* header */,
+    // header
+    is(table.tbody.children[i * 2].firstChild.children.length, 9 + 1,
        "Correct rows in column " + i);
     is(table.tbody.children[i * 2].firstChild.firstChild.value, "Column " + i,
        "Correct column header value");
@@ -189,7 +190,7 @@ function testAPI() {
   is(node2.getAttribute("data-id"), "id7", "Correct node selected");
 
   // test if selectedIRow getter works
-  is(table.selectedRow["col1"], "id7", "Correct result of selectedRow getter");
+  is(table.selectedRow.col1, "id7", "Correct result of selectedRow getter");
 
   // test if isSelected works
   ok(table.isSelected("id7"), "isSelected with column id works");
@@ -209,7 +210,7 @@ function testAPI() {
   is(node3.getAttribute("data-id"), "id4", "Correct node selected");
 
   // test if selectedRow getter works
-  is(table.selectedRow["col1"], "id4", "Correct result of selectedRow getter");
+  is(table.selectedRow.col1, "id4", "Correct result of selectedRow getter");
 
   // test if clear selection works
   table.clearSelection();
@@ -280,10 +281,12 @@ function testAPI() {
 
   // testing if clear works
   table.clear();
-  is(table.tbody.children.length, 4*2 /* double because splitters */,
+  // double because splitters
+  is(table.tbody.children.length, 4 * 2,
      "4 columns exist even after clear");
   for (let i = 0; i < 4; i++) {
-    is(table.tbody.children[i*2].firstChild.children.length, 1 /* header */,
+    // header
+    is(table.tbody.children[i*2].firstChild.children.length, 1,
        "Only header in the column " + i + " after clear call");
     is(table.tbody.children[i*2].firstChild.firstChild.value, "Column " + (i + 1),
        "Correct column header value");
@@ -295,7 +298,8 @@ function testAPI() {
     col2: "Testing"
   });
 
-  is(table.tbody.children.length, 2*2 /* double because splitters */,
+  // double because splitters
+  is(table.tbody.children.length, 2 * 2,
      "2 columns exist after setColumn call");
   is(table.tbody.children[0].firstChild.firstChild.value, "Foobar",
      "Correct column header value for first column");
@@ -308,7 +312,8 @@ function testAPI() {
     col3: "Column 3",
     col4: "Column 4"
   });
-  is(table.tbody.children.length, 4*2 /* double because splitters */,
+  // double because splitters
+  is(table.tbody.children.length, 4 * 2,
      "4 columns exist after second setColumn call");
 
   populateTable();
diff --git a/toolkit/devtools/shared/test/browser_tableWidget_mouse_interaction.js b/toolkit/devtools/shared/test/browser_tableWidget_mouse_interaction.js
index 32cb0e4c58..21b9da8aaa 100644
--- a/toolkit/devtools/shared/test/browser_tableWidget_mouse_interaction.js
+++ b/toolkit/devtools/shared/test/browser_tableWidget_mouse_interaction.js
@@ -146,7 +146,7 @@ let testMouseInteraction = Task.async(function*() {
   ok(node.classList.contains("theme-selected"), "Node has selected class after click");
   is(id, "id1", "Correct row was selected");
 
-  info("clicking on third row to select it");
+  info("clicking on second row to select it");
   event = table.once(TableWidget.EVENTS.ROW_SELECTED);
   let node2 = table.tbody.firstChild.firstChild.children[3];
   // node should not have selected class
@@ -156,7 +156,7 @@ let testMouseInteraction = Task.async(function*() {
   id = yield event;
   ok(node2.classList.contains("theme-selected"),
      "New node has selected class after clicking");
-  is(id, "id3", "Correct table path is emitted for new node")
+  is(id, "id3", "Correct table path is emitted for new node");
   isnot(node, node2, "Old and new node are different");
   ok(!node.classList.contains("theme-selected"),
      "Old node should not have selected class after the click on new node");
diff --git a/toolkit/devtools/shared/test/head.js b/toolkit/devtools/shared/test/head.js
index 18158931bf..752ead4efe 100644
--- a/toolkit/devtools/shared/test/head.js
+++ b/toolkit/devtools/shared/test/head.js
@@ -120,8 +120,7 @@ function waitForValue(aOptions)
     if (successful) {
       ok(true, aOptions.name);
       successFn(aOptions, lastValue);
-    }
-    else {
+    } else {
       setTimeout(function() wait(validatorFn, successFn, failureFn), 100);
     }
   }
@@ -130,7 +129,7 @@ function waitForValue(aOptions)
 }
 
 function oneTimeObserve(name, callback) {
-  var func = function() {
+  let func = function() {
     Services.obs.removeObserver(func, name);
     callback();
   };
@@ -158,10 +157,10 @@ let createHost = Task.async(function*(type = "bottom", src = "data:text/html;cha
  * @param {String} toolId
  */
 function* openAndCloseToolbox(nbOfTimes, usageTime, toolId) {
-  for (let i = 0; i < nbOfTimes; i ++) {
+  for (let i = 0; i < nbOfTimes; i++) {
     info("Opening toolbox " + (i + 1));
     let target = TargetFactory.forTab(gBrowser.selectedTab);
-    yield gDevTools.showToolbox(target, toolId)
+    yield gDevTools.showToolbox(target, toolId);
 
     // We use a timeout to check the toolbox's active time
     yield new Promise(resolve => setTimeout(resolve, usageTime));
diff --git a/toolkit/devtools/shared/widgets/TableWidget.js b/toolkit/devtools/shared/widgets/TableWidget.js
index e3f6ea5493..5ed5cdb388 100644
--- a/toolkit/devtools/shared/widgets/TableWidget.js
+++ b/toolkit/devtools/shared/widgets/TableWidget.js
@@ -818,11 +818,13 @@ Column.prototype = {
    * for sorting.
    */
   onClick: function(event) {
-    if (event.originalTarget == this.column) {
+    let target = event.originalTarget;
+
+    if (target.nodeType !== target.ELEMENT_NODE || target == this.column) {
       return;
     }
 
-    if (event.button == 0 && event.originalTarget == this.header) {
+    if (event.button == 0 && target == this.header) {
       return this.table.sortBy(this.id);
     }
   },
@@ -831,22 +833,20 @@ Column.prototype = {
    * Mousedown event handler for the column. Used to select rows.
    */
   onMousedown: function(event) {
-    if (event.originalTarget == this.column ||
-        event.originalTarget == this.header) {
+    let target = event.originalTarget;
+
+    if (target.nodeType !== target.ELEMENT_NODE ||
+        target == this.column ||
+        target == this.header) {
       return;
     }
     if (event.button == 0) {
-      let target = event.originalTarget;
-      let dataid = null;
-
-      while (target) {
-        dataid = target.getAttribute("data-id");
-        if (dataid) {
-          break;
-        }
-        target = target.parentNode;
+      let closest = target.closest("[data-id]");
+      if (!closest) {
+        return;
       }
 
+      let dataid = closest.getAttribute("data-id");
       this.table.emit(EVENTS.ROW_SELECTED, dataid);
     }
   },
@@ -962,7 +962,7 @@ Cell.prototype = {
   },
 
   /**
-   * Flashes the cell for a brief time. This when done for ith cells in all
+   * Flashes the cell for a brief time. This when done for with cells in all
    * columns, makes it look like the row is being highlighted/flashed.
    */
   flash: function() {
diff --git a/toolkit/devtools/storage/test/browser_storage_values.js b/toolkit/devtools/storage/test/browser_storage_values.js
index e75259312d..3e8e4f9bd9 100644
--- a/toolkit/devtools/storage/test/browser_storage_values.js
+++ b/toolkit/devtools/storage/test/browser_storage_values.js
@@ -27,7 +27,7 @@ const testCases = [
     {name: "c1.isDomain", value: "false"},
     {name: "c1.isHttpOnly", value: "false"},
     {name: "c1.host", value: "test1.example.org"},
-    {name: "c1.expires", value: new Date(2000000000000).toLocaleString()},
+    {name: "c1.expires", value: new Date(2000000000000).toUTCString()},
     {name: "c1.isSecure", value: "false"},
   ]],
   [/*"c1"*/, [
diff --git a/toolkit/devtools/storage/ui.js b/toolkit/devtools/storage/ui.js
index 1139c67aa7..781bb7332a 100644
--- a/toolkit/devtools/storage/ui.js
+++ b/toolkit/devtools/storage/ui.js
@@ -444,8 +444,8 @@ StorageUI.prototype = {
         let p = separators[j];
         let regex = new RegExp("^([^" + kv + p + "]*" + kv + "+[^" + kv + p +
                                "]*" + p + "*)+$", "g");
-        if (value.match(regex) && value.contains(kv) &&
-            (value.contains(p) || value.split(kv).length == 2)) {
+        if (value.match && value.match(regex) && value.includes(kv) &&
+            (value.includes(p) || value.split(kv).length == 2)) {
           return makeObject(kv, p);
         }
       }
@@ -454,7 +454,7 @@ StorageUI.prototype = {
     for (let i = 0; i < separators.length; i++) {
       let p = separators[i];
       let regex = new RegExp("^[^" + p + "]+(" + p + "+[^" + p + "]*)+$", "g");
-      if (value.match(regex)) {
+      if (value.match && value.match(regex)) {
         return value.split(p.replace(/\\*/g, ""));
       }
     }
@@ -534,14 +534,14 @@ StorageUI.prototype = {
       }
       if (item.expires != null) {
         item.expires = item.expires
-          ? new Date(item.expires).toLocaleString()
+          ? new Date(item.expires).toUTCString()
           : L10N.getStr("label.expires.session");
       }
       if (item.creationTime != null) {
-        item.creationTime = new Date(item.creationTime).toLocaleString();
+        item.creationTime = new Date(item.creationTime).toUTCString();
       }
       if (item.lastAccessed != null) {
-        item.lastAccessed = new Date(item.lastAccessed).toLocaleString();
+        item.lastAccessed = new Date(item.lastAccessed).toUTCString();
       }
       if (reason < 2) {
         this.table.push(item, reason == 0);