--- a/accessible/tests/browser/general/browser_test_urlbar.js
+++ b/accessible/tests/browser/general/browser_test_urlbar.js
@@ -10,17 +10,17 @@ add_task(async function testAutocomplete
   let tab = await openNewTab("data:text/html;charset=utf-8,");
   let accService = await initAccessibilityService();
 
   info("Opening the URL bar and entering a key to show the PopupAutoCompleteRichResult panel");
   let urlbar = document.getElementById("urlbar");
   urlbar.focus();
   let urlbarPopup = document.getElementById("PopupAutoCompleteRichResult");
   let shown = BrowserTestUtils.waitForEvent(urlbarPopup, "popupshown");
-  EventUtils.synthesizeKey("a", {});
+  EventUtils.sendString("a");
   await shown;
 
   info("Waiting for accessibility to be created for the richlistbox");
   let richlistbox = document.getAnonymousElementByAttribute(urlbarPopup, "anonid", "richlistbox");
   await BrowserTestUtils.waitForCondition(() => accService.getAccessibleFor(richlistbox));
 
   info("Confirming that the special case is handled in XULListboxAccessible");
   let accessible = accService.getAccessibleFor(richlistbox);

--- a/accessible/tests/mochitest/events.js
+++ b/accessible/tests/mochitest/events.js
@@ -1400,17 +1400,17 @@ function openCombobox(aComboboxID) {
  * Close combobox, autocomplete and etc popup, check expandable states.
  */
 function closeCombobox(aComboboxID) {
   this.eventSeq = [
     new stateChangeChecker(STATE_EXPANDED, false, false, aComboboxID)
   ];
 
   this.invoke = function closeCombobox_invoke() {
-    synthesizeKey("VK_ESCAPE", { });
+    synthesizeKey("KEY_Escape");
   };
 
   this.getID = function closeCombobox_getID() {
     return "close combobox " + prettyName(aComboboxID);
   };
 }
 
 
@@ -1454,22 +1454,22 @@ function moveToLineEnd(aID, aCaretOffset
 
 /**
  * Move the caret to the end of previous line if any.
  */
 function moveToPrevLineEnd(aID, aCaretOffset) {
   this.__proto__ = new synthAction(aID, new caretMoveChecker(aCaretOffset, aID));
 
   this.invoke = function moveToPrevLineEnd_invoke() {
-    synthesizeKey("VK_UP", { });
+    synthesizeKey("KEY_ArrowUp");
 
     if (MAC)
-      synthesizeKey("VK_RIGHT", { metaKey: true });
+      synthesizeKey("Key_ArrowRight", {metaKey: true});
     else
-      synthesizeKey("VK_END", { });
+      synthesizeKey("KEY_End");
   };
 
   this.getID = function moveToPrevLineEnd_getID() {
     return "move to previous line end in " + prettyName(aID);
   };
 }
 
 /**

--- a/accessible/tests/mochitest/events/test_contextmenu.html
+++ b/accessible/tests/mochitest/events/test_contextmenu.html
@@ -41,32 +41,32 @@
     }
 
     function selectMenuItem() {
       this.eventSeq = [
         new invokerChecker(EVENT_FOCUS, getFocusedMenuItem)
       ];
 
       this.invoke = function selectMenuItem_invoke() {
-        synthesizeKey("VK_DOWN", { });
+        synthesizeKey("KEY_ArrowDown");
       };
 
       this.getID = function selectMenuItem_getID() {
         return "select first menuitem";
       };
     }
 
     function closeContextMenu(aID) {
       this.eventSeq = [
         new invokerChecker(EVENT_MENUPOPUP_END,
                            getAccessible(getContextMenuNode()))
       ];
 
       this.invoke = function closeContextMenu_invoke() {
-        synthesizeKey("VK_ESCAPE", { });
+        synthesizeKey("KEY_Escape");
       };
 
       this.getID = function closeContextMenu_getID() {
         return "close context menu";
       };
     }
 
     function getContextMenuNode() {

--- a/accessible/tests/mochitest/events/test_focus_autocomplete.xul
+++ b/accessible/tests/mochitest/events/test_focus_autocomplete.xul
@@ -122,34 +122,34 @@
     }
 
     function removeChar(aID, aCheckerOrEventSeq)
     {
       this.__proto__ = new synthAction(aID, aCheckerOrEventSeq);
 
       this.invoke = function removeChar_invoke()
       {
-        synthesizeKey("VK_LEFT", { shiftKey: true });
-        synthesizeKey("VK_DELETE", {});
+        synthesizeKey("KEY_ArrowLeft", {shiftKey: true});
+        synthesizeKey("KEY_Delete");
       }
 
       this.getID = function removeChar_getID()
       {
         return "remove char on " + prettyName(aID);
       }
     }
 
     function replaceOnChar(aID, aChar, aCheckerOrEventSeq)
     {
       this.__proto__ = new synthAction(aID, aCheckerOrEventSeq);
 
       this.invoke = function replaceOnChar_invoke()
       {
         this.DOMNode.select();
-        synthesizeKey(aChar, {});
+        sendString(aChar);
       }
 
       this.getID = function replaceOnChar_getID()
       {
         return "replace on char '" + aChar + "' for" + prettyName(aID);
       }
     }
 

--- a/accessible/tests/mochitest/events/test_fromUserInput.html
+++ b/accessible/tests/mochitest/events/test_fromUserInput.html
@@ -27,17 +27,17 @@
       this.eventSeq = [
         new textChangeChecker(aID, aStart, aEnd, aText, false, aFromUser)
       ];
 
       this.invoke = function removeTextFromInput_invoke() {
         this.DOMNode.focus();
         this.DOMNode.setSelectionRange(aStart, aEnd);
 
-        synthesizeKey("VK_DELETE", {});
+        synthesizeKey("KEY_Delete");
       };
 
       this.getID = function removeTextFromInput_getID() {
         return "Remove text from " + aStart + " to " + aEnd + " for " +
           prettyName(aID);
       };
     }
 
@@ -55,17 +55,17 @@
         this.DOMNode.focus();
         this.textNode = getNode(aID).firstChild;
         var selection = window.getSelection();
         var range = document.createRange();
         range.setStart(this.textNode, aStart);
         range.setEnd(this.textNode, aEnd);
         selection.addRange(range);
 
-        synthesizeKey("VK_DELETE", {});
+        synthesizeKey("KEY_Delete");
       };
 
       this.getID = function removeTextFromContentEditable_getID() {
         return "Remove text from " + aStart + " to " + aEnd + " for " +
           prettyName(aID);
       };
     }
 

--- a/accessible/tests/mochitest/events/test_menu.xul
+++ b/accessible/tests/mochitest/events/test_menu.xul
@@ -22,17 +22,17 @@
       this.eventSeq = [
         new invokerChecker(EVENT_MENU_START, getNode("menubar")),
         new invokerChecker(EVENT_MENUPOPUP_START, getNode("menupopup-file"))
         // new invokerChecker(EVENT_FOCUS, getNode("menuitem-newtab")) intermitent failure
       ];
 
       this.invoke = function openFileMenu_invoke()
       {
-        synthesizeKey("F", { altKey: true, shiftKey: true });
+        synthesizeKey("F", {altKey: true, shiftKey: true});
       }
 
       this.getID = function openFileMenu_getID()
       {
         return "open file menu by alt+F press";
       }
     }
 
@@ -41,17 +41,17 @@
       this.eventSeq = [
         new invokerChecker(EVENT_MENUPOPUP_END, getNode("menupopup-file")),
         new invokerChecker(EVENT_MENUPOPUP_START, getNode("menupopup-edit"))
         // new invokerChecker(EVENT_FOCUS, getNode("menuitem-undo")) intermitent failure
       ];
 
       this.invoke = function openEditMenu_invoke()
       {
-        synthesizeKey("VK_RIGHT", { });
+        synthesizeKey("KEY_ArrowRight");
       }
 
       this.getID = function openEditMenu_getID()
       {
         return "open edit menu by lef arrow press";
       }
     }
 
@@ -60,17 +60,17 @@
       this.eventSeq = [
         //new invokerChecker(EVENT_FOCUS, document), intermitent failure
         new invokerChecker(EVENT_MENUPOPUP_END, getNode("menupopup-edit")),
         new invokerChecker(EVENT_MENU_END, getNode("menubar"))
       ];
 
       this.invoke = function closeEditMenu_invoke()
       {
-        synthesizeKey("VK_ESCAPE", { });
+        synthesizeKey("KEY_Escape");
       }
 
       this.getID = function closeEditMenu_getID()
       {
         return "close edit menu, leave menubar";
       }
     }
 
@@ -78,34 +78,34 @@
     {
       this.eventSeq = [
         new invokerChecker(EVENT_MENU_START, getNode("menubar"))
         // new invokerChecker(EVENT_FOCUS, getNode("menuitem-file")) //intermitent failure
       ];
 
       this.invoke = function focusFileMenu_invoke()
       {
-        synthesizeKey("VK_ALT", { });
+        synthesizeKey("KEY_Alt");
       }
 
       this.getID = function focusFileMenu_getID()
       {
         return "activate menubar, focus file menu (atl press)";
       }
     }
 
     function focusEditMenu()
     {
       this.eventSeq = [
         new invokerChecker(EVENT_FOCUS, getNode("menuitem-edit"))
       ];
 
       this.invoke = function focusEditMenu_invoke()
       {
-        synthesizeKey("VK_RIGHT", { });
+        synthesizeKey("KEY_ArrowRight");
       }
 
       this.getID = function focusEditMenu_getID()
       {
         return "focus edit menu";
       }
     }
 
@@ -113,17 +113,17 @@
     {
       this.eventSeq = [
         //new invokerChecker(EVENT_FOCUS, document), intermitent failure
         new invokerChecker(EVENT_MENU_END, getNode("menubar"))
       ];
 
       this.invoke = function leaveMenubar_invoke()
       {
-        synthesizeKey("VK_ESCAPE", { });
+        synthesizeKey("KEY_Escape");
       }
 
       this.getID = function leaveMenubar_getID()
       {
         return "leave menubar";
       }
     }
 

--- a/accessible/tests/mochitest/events/test_text.html
+++ b/accessible/tests/mochitest/events/test_text.html
@@ -164,17 +164,17 @@
 
       this.eventSeq.push(new invokerChecker(EVENT_TEXT_VALUE_CHANGE,
                                             this.DOMNode));
 
       this.invoke = function removeTextFromInput_invoke() {
         this.DOMNode.focus();
         this.DOMNode.setSelectionRange(aStart, aEnd);
 
-        synthesizeKey("VK_DELETE", {});
+        synthesizeKey("KEY_Delete");
       };
 
       this.getID = function removeTextFromInput_getID() {
         return "Remove text from " + aStart + " to " + aEnd + " for " +
           prettyName(aID);
       };
     }
 
@@ -184,17 +184,17 @@
     function insertTextIntoInput(aID, aStart, aEnd, aText) {
       this.__proto__ = new textInsertInvoker(aID, aStart, aEnd, aText);
 
       this.eventSeq.push(new invokerChecker(EVENT_TEXT_VALUE_CHANGE,
                                             this.DOMNode));
 
       this.invoke = function insertTextIntoInput_invoke() {
         this.DOMNode.focus();
-        synthesizeKey("a", {});
+        sendString("a");
       };
 
       this.getID = function insertTextIntoInput_getID() {
         return "Insert text to " + aStart + " for " + prettyName(aID);
       };
     }
 
     /**
@@ -207,17 +207,17 @@
         this.DOMNode.focus();
 
         var selection = window.getSelection();
         var range = document.createRange();
         range.setStart(this.textNode, aStart);
         range.setEnd(this.textNode, aEnd);
         selection.addRange(range);
 
-        synthesizeKey("VK_DELETE", {});
+        synthesizeKey("KEY_Delete");
       };
 
       this.getID = function removeTextFromEditable_getID() {
         return "Remove text from " + aStart + " to " + aEnd + " for " +
           prettyName(aID);
       };
 
       this.textNode = getNode(aTextNode);

--- a/accessible/tests/mochitest/states/test_inputs.html
+++ b/accessible/tests/mochitest/states/test_inputs.html
@@ -102,17 +102,17 @@
     }
 
     // //////////////////////////////////////////////////////////////////////////
     // 'invalid' state
     // (per spec, min/maxlength validity is affected by interactive edits)
     var mininp = document.getElementById("minlength");
     mininp.focus();
     mininp.setSelectionRange(mininp.value.length, mininp.value.length);
-    synthesizeKey("VK_BACK_SPACE", {});
+    synthesizeKey("KEY_Backspace");
     ok(!mininp.validity.valid,
        "input should be invalid after interactive edits");
     testStates(mininp, STATE_INVALID);
     // inputs currently cannot be made longer than maxlength interactively,
     // so we're not testing that case.
 
     // //////////////////////////////////////////////////////////////////////////
     // autocomplete states

--- a/accessible/tests/mochitest/treeupdate/test_contextmenu.xul
+++ b/accessible/tests/mochitest/treeupdate/test_contextmenu.xul
@@ -47,34 +47,34 @@
     function selectNextMenuItem(aID)
     {
       this.eventSeq = [
         new invokerChecker(EVENT_FOCUS, getNode(aID))
       ];
 
       this.invoke = function selectMenuItem_invoke()
       {
-        synthesizeKey("VK_DOWN", { });
+        synthesizeKey("KEY_ArrowDown");
       }
 
       this.getID = function selectMenuItem_getID()
       {
         return "select menuitem " + prettyName(aID);
       }
     }
     
     function openSubMenu(aSubMenuID, aItemID, aMenuID, aTree)
     {
       this.eventSeq = [
         new invokerChecker(EVENT_FOCUS, getNode(aItemID)),
       ];
 
       this.invoke = function openSubMenu_invoke()
       {
-        synthesizeKey("VK_RETURN", { });
+        synthesizeKey("KEY_Enter");
       }
 
       this.finalCheck = function openSubMenu_finalCheck(aEvent)
       {
         testAccessibleTree(aMenuID, aTree);
       }
 
       this.getID = function openSubMenu_getID()
@@ -86,34 +86,34 @@
     function closeSubMenu(aSubMenuID, aItemID)
     {
       this.eventSeq = [
         new invokerChecker(EVENT_FOCUS, getNode(aItemID)),
       ];
 
       this.invoke = function closeSubMenu_invoke()
       {
-        synthesizeKey("VK_ESCAPE", { });
+        synthesizeKey("KEY_Escape");
       }
 
       this.getID = function closeSubMenu_getID()
       {
         return "close submenu " + prettyName(aSubMenuID) + " focusing item " + prettyName(aItemID);
       }
     }
 
     function closeMenu(aID)
     {
       this.eventSeq = [
         new invokerChecker(EVENT_MENUPOPUP_END, getNode(aID))
       ];
 
       this.invoke = function closeMenu_invoke()
       {
-        synthesizeKey("VK_ESCAPE", { });
+        synthesizeKey("KEY_Escape");
       }
 
       this.getID = function closeMenu_getID()
       {
         return "close menu " + prettyName(aID);
       }
     }
 

--- a/accessible/tests/mochitest/treeupdate/test_menubutton.xul
+++ b/accessible/tests/mochitest/treeupdate/test_menubutton.xul
@@ -50,17 +50,17 @@
           { PUSHBUTTON: [
             { MENUPOPUP: [
               { role: menuItemRole, children: [ ] },
               { role: menuItemRole, children: [ ] }
             ] }
           ] };
         testAccessibleTree(this.button, tree);
 
-        synthesizeKey("VK_ESCAPE", { });
+        synthesizeKey("KEY_Escape");
       }
 
       this.getID = function openMenu_getID()
       {
         return "open menu of the button " + prettyName(aButtonID);
       }
     }
 

--- a/browser/base/content/test/forms/browser_selectpopup.js
+++ b/browser/base/content/test/forms/browser_selectpopup.js
@@ -139,36 +139,36 @@ async function doSelectTests(contentType
   let isWindows = navigator.platform.includes("Win");
 
   is(menulist.selectedIndex, 1, "Initial selection");
   is(selectPopup.firstChild.localName, "menucaption", "optgroup is caption");
   is(selectPopup.firstChild.getAttribute("label"), "First Group", "optgroup label");
   is(selectPopup.childNodes[1].localName, "menuitem", "option is menuitem");
   is(selectPopup.childNodes[1].getAttribute("label"), "One", "option label");
 
-  EventUtils.synthesizeKey("KEY_ArrowDown", {});
+  EventUtils.synthesizeKey("KEY_ArrowDown");
   is(menulist.menuBoxObject.activeChild, menulist.getItemAtIndex(2), "Select item 2");
   is(menulist.selectedIndex, isWindows ? 2 : 1, "Select item 2 selectedIndex");
 
-  EventUtils.synthesizeKey("KEY_ArrowDown", {});
+  EventUtils.synthesizeKey("KEY_ArrowDown");
   is(menulist.menuBoxObject.activeChild, menulist.getItemAtIndex(3), "Select item 3");
   is(menulist.selectedIndex, isWindows ? 3 : 1, "Select item 3 selectedIndex");
 
-  EventUtils.synthesizeKey("KEY_ArrowDown", {});
+  EventUtils.synthesizeKey("KEY_ArrowDown");
 
   // On Windows, one can navigate on disabled menuitems
   is(menulist.menuBoxObject.activeChild, menulist.getItemAtIndex(9),
      "Skip optgroup header and disabled items select item 7");
   is(menulist.selectedIndex, isWindows ? 9 : 1, "Select or skip disabled item selectedIndex");
 
   for (let i = 0; i < 10; i++) {
     is(menulist.getItemAtIndex(i).disabled, i >= 4 && i <= 7, "item " + i + " disabled");
   }
 
-  EventUtils.synthesizeKey("KEY_ArrowUp", {});
+  EventUtils.synthesizeKey("KEY_ArrowUp");
   is(menulist.menuBoxObject.activeChild, menulist.getItemAtIndex(3), "Select item 3 again");
   is(menulist.selectedIndex, isWindows ? 3 : 1, "Select item 3 selectedIndex");
 
   is((await getInputEvents()), 0, "Before closed - number of input events");
   is((await getChangeEvents()), 0, "Before closed - number of change events");
   is((await getClickEvents()), 0, "Before closed - number of click events");
 
   EventUtils.synthesizeKey("a", { accelKey: true });
@@ -177,46 +177,46 @@ async function doSelectTests(contentType
       "Select all while popup is open");
   });
 
   // Backspace should not go back
   let handleKeyPress = function(event) {
     ok(false, "Should not get keypress event");
   };
   window.addEventListener("keypress", handleKeyPress);
-  EventUtils.synthesizeKey("VK_BACK_SPACE", { });
+  EventUtils.synthesizeKey("KEY_Backspace");
   window.removeEventListener("keypress", handleKeyPress);
 
   await hideSelectPopup(selectPopup);
 
   is(menulist.selectedIndex, 3, "Item 3 still selected");
   is((await getInputEvents()), 1, "After closed - number of input events");
   is((await getChangeEvents()), 1, "After closed - number of change events");
   is((await getClickEvents()), 0, "After closed - number of click events");
 
   // Opening and closing the popup without changing the value should not fire a change event.
   await openSelectPopup(selectPopup, "click");
   await hideSelectPopup(selectPopup, "escape");
   is((await getInputEvents()), 1, "Open and close with no change - number of input events");
   is((await getChangeEvents()), 1, "Open and close with no change - number of change events");
   is((await getClickEvents()), 1, "Open and close with no change - number of click events");
-  EventUtils.synthesizeKey("VK_TAB", { });
-  EventUtils.synthesizeKey("VK_TAB", { shiftKey: true });
+  EventUtils.synthesizeKey("KEY_Tab");
+  EventUtils.synthesizeKey("KEY_Tab", {shiftKey: true});
   is((await getInputEvents()), 1, "Tab away from select with no change - number of input events");
   is((await getChangeEvents()), 1, "Tab away from select with no change - number of change events");
   is((await getClickEvents()), 1, "Tab away from select with no change - number of click events");
 
   await openSelectPopup(selectPopup, "click");
-  EventUtils.synthesizeKey("KEY_ArrowDown", {});
+  EventUtils.synthesizeKey("KEY_ArrowDown");
   await hideSelectPopup(selectPopup, "escape");
   is((await getInputEvents()), isWindows ? 2 : 1, "Open and close with change - number of input events");
   is((await getChangeEvents()), isWindows ? 2 : 1, "Open and close with change - number of change events");
   is((await getClickEvents()), 2, "Open and close with change - number of click events");
-  EventUtils.synthesizeKey("VK_TAB", { });
-  EventUtils.synthesizeKey("VK_TAB", { shiftKey: true });
+  EventUtils.synthesizeKey("KEY_Tab");
+  EventUtils.synthesizeKey("KEY_Tab", {shiftKey: true});
   is((await getInputEvents()), isWindows ? 2 : 1, "Tab away from select with change - number of input events");
   is((await getChangeEvents()), isWindows ? 2 : 1, "Tab away from select with change - number of change events");
   is((await getClickEvents()), 2, "Tab away from select with change - number of click events");
 
   is(selectPopup.lastChild.previousSibling.label, "Seven", "Spaces collapsed");
   is(selectPopup.lastChild.label, "\xA0\xA0Eight\xA0\xA0", "Non-breaking spaces not collapsed");
 
   await BrowserTestUtils.removeTab(tab);
@@ -430,17 +430,17 @@ add_task(async function test_event_order
 
           let select = content.document.getElementById(contentMode == "enter" ? "one" : "two");
           for (let event of ["input", "change", "mousedown", "mouseup", "click"]) {
             select.addEventListener(event, onEvent);
           }
         });
       });
 
-      EventUtils.synthesizeKey("KEY_ArrowDown", {});
+      EventUtils.synthesizeKey("KEY_ArrowDown");
       await hideSelectPopup(selectPopup, mode);
       await eventsPromise;
     }
   });
 });
 
 async function performLargePopupTests(win) {
   let browser = win.gBrowser.selectedBrowser;
@@ -632,32 +632,32 @@ async function performSelectSearchTests(
   is(selectPopup.childNodes[2].hidden, true, "First option should be hidden");
   is(selectPopup.childNodes[3].hidden, true, "Second option should be hidden");
   is(selectPopup.childNodes[4].hidden, false, "Third option should be visible");
 
   EventUtils.synthesizeKey("Z", {}, win);
   is(selectPopup.childNodes[4].hidden, true, "Third option should be hidden");
   is(selectPopup.childNodes[1].hidden, true, "First group header should be hidden");
 
-  EventUtils.synthesizeKey("VK_BACK_SPACE", {}, win);
+  EventUtils.synthesizeKey("KEY_Backspace", {}, win);
   is(selectPopup.childNodes[4].hidden, false, "Third option should be visible");
 
-  EventUtils.synthesizeKey("VK_BACK_SPACE", {}, win);
+  EventUtils.synthesizeKey("KEY_Backspace", {}, win);
   is(selectPopup.childNodes[5].hidden, false, "Second group header should be visible");
 
-  EventUtils.synthesizeKey("VK_BACK_SPACE", {}, win);
+  EventUtils.synthesizeKey("KEY_Backspace", {}, win);
   EventUtils.synthesizeKey("O", {}, win);
   EventUtils.synthesizeKey("5", {}, win);
   is(selectPopup.childNodes[5].hidden, false, "Second group header should be visible");
   is(selectPopup.childNodes[1].hidden, true, "First group header should be hidden");
 
-  EventUtils.synthesizeKey("VK_BACK_SPACE", {}, win);
+  EventUtils.synthesizeKey("KEY_Backspace", {}, win);
   is(selectPopup.childNodes[1].hidden, false, "First group header should be shown");
 
-  EventUtils.synthesizeKey("VK_BACK_SPACE", {}, win);
+  EventUtils.synthesizeKey("KEY_Backspace", {}, win);
   is(selectPopup.childNodes[8].hidden, true, "Option hidden by content should remain hidden");
 
   await hideSelectPopup(selectPopup, "escape", win);
 }
 
 // This test checks the functionality of search in select elements with groups
 // and a large number of options.
 add_task(async function test_select_search() {

--- a/browser/base/content/test/forms/browser_selectpopup_colors.js
+++ b/browser/base/content/test/forms/browser_selectpopup_colors.js
@@ -198,17 +198,17 @@ function testOptionColors(index, item, m
     if (color.toLowerCase().includes("color") &&
         !expected[color].startsWith("rgb")) {
       expected[color] = getSystemColor(expected[color]);
     }
   }
 
   // Press Down to move the selected item to the next item in the
   // list and check the colors of this item when it's not selected.
-  EventUtils.synthesizeKey("KEY_ArrowDown", {});
+  EventUtils.synthesizeKey("KEY_ArrowDown");
 
   if (expected.end) {
     return;
   }
 
   if (expected.unstyled) {
     ok(!item.hasAttribute("customoptionstyling"),
       `Item ${index} should not have any custom option styling`);

--- a/browser/base/content/test/general/browser_bug432599.js
+++ b/browser/base/content/test/general/browser_bug432599.js
@@ -1,33 +1,33 @@
 /* eslint-disable mozilla/no-arbitrary-setTimeout */
 function invokeUsingCtrlD(phase) {
   switch (phase) {
   case 1:
-    EventUtils.synthesizeKey("d", { accelKey: true });
+    EventUtils.synthesizeKey("d", {accelKey: true});
     break;
   case 2:
   case 4:
-    EventUtils.synthesizeKey("VK_ESCAPE", {});
+    EventUtils.synthesizeKey("KEY_Escape");
     break;
   case 3:
-    EventUtils.synthesizeKey("d", { accelKey: true });
-    EventUtils.synthesizeKey("d", { accelKey: true });
+    EventUtils.synthesizeKey("d", {accelKey: true});
+    EventUtils.synthesizeKey("d", {accelKey: true});
     break;
   }
 }
 
 function invokeUsingStarButton(phase) {
   switch (phase) {
   case 1:
      EventUtils.synthesizeMouseAtCenter(BookmarkingUI.star, {});
     break;
   case 2:
   case 4:
-    EventUtils.synthesizeKey("VK_ESCAPE", {});
+    EventUtils.synthesizeKey("KEY_Escape");
     break;
   case 3:
      EventUtils.synthesizeMouseAtCenter(BookmarkingUI.star,
                                         { clickCount: 2 });
     break;
   }
 }
 

--- a/browser/base/content/test/general/browser_bug553455.js
+++ b/browser/base/content/test/general/browser_bug553455.js
@@ -689,17 +689,17 @@ async function test_tabNavigate() {
 async function test_urlBar() {
   let progressPromise = waitForProgressNotification();
   let dialogPromise = waitForInstallDialog();
 
   gBrowser.selectedTab = BrowserTestUtils.addTab(gBrowser, "about:blank");
   await BrowserTestUtils.browserLoaded(gBrowser.selectedBrowser);
   gURLBar.value = TESTROOT + "amosigned.xpi";
   gURLBar.focus();
-  EventUtils.synthesizeKey("VK_RETURN", {});
+  EventUtils.synthesizeKey("KEY_Enter");
 
   await progressPromise;
   let installDialog = await dialogPromise;
 
   let notificationPromise = waitForNotification("addon-install-restart");
   acceptInstallDialog(installDialog);
   let panel = await notificationPromise;
 

--- a/browser/base/content/test/general/browser_bug555767.js
+++ b/browser/base/content/test/general/browser_bug555767.js
@@ -44,10 +44,10 @@
         tabSelected = true;
       }
 
       // Add the TabClose, TabSelect event listeners before we press enter
       gBrowser.tabContainer.addEventListener("TabClose", onTabClose);
       gBrowser.tabContainer.addEventListener("TabSelect", onTabSelect);
 
       // Press enter!
-      EventUtils.synthesizeKey("VK_RETURN", {});
+      EventUtils.synthesizeKey("KEY_Enter");
     });

--- a/browser/base/content/test/general/browser_domFullscreen_fullscreenMode.js
+++ b/browser/base/content/test/general/browser_domFullscreen_fullscreenMode.js
@@ -123,24 +123,24 @@ var gTests = [
     exitFunc: () => {
       gMessageManager.sendAsyncMessage("Test:ExitFullscreen");
     }
   },
   {
     desc: "escape key",
     affectsFullscreenMode: false,
     exitFunc: () => {
-      executeSoon(() => EventUtils.synthesizeKey("VK_ESCAPE", {}));
+      executeSoon(() => EventUtils.synthesizeKey("KEY_Escape"));
     }
   },
   {
     desc: "F11 key",
     affectsFullscreenMode: true,
     exitFunc() {
-      executeSoon(() => EventUtils.synthesizeKey("VK_F11", {}));
+      executeSoon(() => EventUtils.synthesizeKey("KEY_F11"));
     }
   }
 ];
 
 function checkState(expectedStates, contentStates) {
   is(contentStates.inDOMFullscreen, expectedStates.inDOMFullscreen,
      "The DOM fullscreen state of the content should match");
   // TODO window.fullScreen is not updated as soon as the fullscreen

--- a/browser/base/content/test/general/browser_focusonkeydown.js
+++ b/browser/base/content/test/general/browser_focusonkeydown.js
@@ -10,14 +10,14 @@ add_task(async function() {
       keyUps++;
     }
   }, {capture: true, once: true});
 
   gURLBar.addEventListener("keydown", function(event) {
     gBrowser.selectedBrowser.focus();
   }, {capture: true, once: true});
 
-  EventUtils.synthesizeKey("v", { });
+  EventUtils.sendString("v");
 
   is(keyUps, 1, "Key up fired at url bar");
 
   gBrowser.removeCurrentTab();
 });

--- a/browser/base/content/test/general/browser_keywordBookmarklets.js
+++ b/browser/base/content/test/general/browser_keywordBookmarklets.js
@@ -19,17 +19,17 @@ add_task(async function test_keyword_boo
   let originalPrincipal = gBrowser.contentPrincipal;
   let originalPrincipalURI = await getPrincipalURI(tab.linkedBrowser);
 
   await PlacesUtils.keywords.insert({ keyword: "bm", url: "javascript:'1';" });
 
   // Enter bookmarklet keyword in the URL bar
   gURLBar.value = "bm";
   gURLBar.focus();
-  EventUtils.synthesizeKey("VK_RETURN", {});
+  EventUtils.synthesizeKey("KEY_Enter");
 
   await BrowserTestUtils.waitForContentEvent(gBrowser.selectedBrowser, "pageshow");
 
   let newPrincipalURI = await getPrincipalURI(tab.linkedBrowser);
   is(newPrincipalURI, originalPrincipalURI, "content has the same principal");
 
   // In e10s, null principals don't round-trip so the same null principal sent
   // from the child will be a new null principal. Verify that this is the

--- a/browser/base/content/test/general/browser_keywordSearch.js
+++ b/browser/base/content/test/general/browser_keywordSearch.js
@@ -114,10 +114,10 @@ function nextTest() {
 }
 
 function doTest() {
   info("Running test: " + gCurrTest.name);
 
   // Simulate a user entering search terms
   gURLBar.value = gCurrTest.testText;
   gURLBar.focus();
-  EventUtils.synthesizeKey("VK_RETURN", {});
+  EventUtils.synthesizeKey("KEY_Enter");
 }

--- a/browser/base/content/test/general/browser_keywordSearch_postData.js
+++ b/browser/base/content/test/general/browser_keywordSearch_postData.js
@@ -73,17 +73,17 @@ function doTest() {
     let needle = "searchterms=" + gCurrTest.expectText;
     is(loadedText, needle, "The query POST data should be returned in the response");
     nextTest();
   });
 
   // Simulate a user entering search terms
   gURLBar.value = gCurrTest.testText;
   gURLBar.focus();
-  EventUtils.synthesizeKey("VK_RETURN", {});
+  EventUtils.synthesizeKey("KEY_Enter");
 }
 
 
 function waitForLoad(cb) {
   let browser = gBrowser.selectedBrowser;
   function wantLoad(url) {
     return url != "about:blank";
   }

--- a/browser/base/content/test/general/browser_printpreview.js
+++ b/browser/base/content/test/general/browser_printpreview.js
@@ -16,35 +16,35 @@ function test() {
   });
 }
 
 function tidyUp() {
   BrowserTestUtils.removeTab(ourTab).then(finish);
 }
 
 function testClosePrintPreviewWithAccessKey() {
-  EventUtils.synthesizeKey("c", { altKey: true });
+  EventUtils.synthesizeKey("c", {altKey: true});
   checkPrintPreviewClosed(function(aSucceeded) {
     ok(aSucceeded,
        "print preview mode should be finished by access key");
     openPrintPreview(testClosePrintPreviewWithEscKey);
   });
 }
 
 function testClosePrintPreviewWithEscKey() {
-  EventUtils.synthesizeKey("VK_ESCAPE", {});
+  EventUtils.synthesizeKey("KEY_Escape");
   checkPrintPreviewClosed(function(aSucceeded) {
     ok(aSucceeded,
        "print preview mode should be finished by Esc key press");
     openPrintPreview(testClosePrintPreviewWithClosingWindowShortcutKey);
   });
 }
 
 function testClosePrintPreviewWithClosingWindowShortcutKey() {
-  EventUtils.synthesizeKey("w", { accelKey: true });
+  EventUtils.synthesizeKey("w", {accelKey: true});
   checkPrintPreviewClosed(function(aSucceeded) {
     ok(aSucceeded,
        "print preview mode should be finished by closing window shortcut key");
     tidyUp();
   });
 }
 
 function openPrintPreview(aCallback) {

--- a/browser/base/content/test/general/browser_tabfocus.js
+++ b/browser/base/content/test/general/browser_tabfocus.js
@@ -339,26 +339,26 @@ add_task(async function() {
 
   // Document navigation with F6 does not yet work in mutli-process browsers.
   if (!gMultiProcessBrowser) {
     gURLBar.focus();
     actualEvents = new EventStore();
     _lastfocus = "urlbar";
     _lastfocuswindow = "main-window";
 
-    await expectFocusShift(() => EventUtils.synthesizeKey("VK_F6", { }),
+    await expectFocusShift(() => EventUtils.synthesizeKey("KEY_F6"),
                            "window1", "html1",
                            true, "switch document forward with f6");
 
-    EventUtils.synthesizeKey("VK_F6", { });
+    EventUtils.synthesizeKey("KEY_F6");
     is(fm.focusedWindow, window, "switch document forward again with f6");
 
     browser1.style.MozUserFocus = "ignore";
     browser1.clientWidth;
-    EventUtils.synthesizeKey("VK_F6", { });
+    EventUtils.synthesizeKey("KEY_F6");
     is(fm.focusedWindow, window, "switch document forward again with f6 when browser non-focusable");
 
     browser1.style.MozUserFocus = "normal";
     browser1.clientWidth;
   }
 
   window.removeEventListener("focus", _browser_tabfocus_test_eventOccured, true);
   window.removeEventListener("blur", _browser_tabfocus_test_eventOccured, true);

--- a/browser/base/content/test/general/browser_visibleFindSelection.js
+++ b/browser/base/content/test/general/browser_visibleFindSelection.js
@@ -6,28 +6,26 @@ add_task(async function() {
   let tab = gBrowser.selectedTab = BrowserTestUtils.addTab(gBrowser);
 
   await promiseTabLoadEvent(tab, "data:text/html;charset=utf-8," + escape(childContent));
   await SimpleTest.promiseFocus(gBrowser.selectedBrowser);
 
   let remote = gBrowser.selectedBrowser.isRemoteBrowser;
 
   let findBarOpenPromise = promiseWaitForEvent(gBrowser, "findbaropen");
-  EventUtils.synthesizeKey("f", { accelKey: true });
+  EventUtils.synthesizeKey("f", {accelKey: true});
   await findBarOpenPromise;
 
   ok(gFindBarInitialized, "find bar is now initialized");
 
   // Finds the div in the green box.
   let scrollPromise = remote ?
     BrowserTestUtils.waitForContentEvent(gBrowser.selectedBrowser, "scroll") :
     BrowserTestUtils.waitForEvent(gBrowser, "scroll");
-  EventUtils.synthesizeKey("d", {});
-  EventUtils.synthesizeKey("i", {});
-  EventUtils.synthesizeKey("v", {});
+  EventUtils.sendString("div");
   await scrollPromise;
 
   // Wait for one paint to ensure we've processed the previous key events and scrolling.
   await ContentTask.spawn(gBrowser.selectedBrowser, null, async function() {
     return new Promise(
       resolve => {
         content.requestAnimationFrame(() => {
           setTimeout(resolve, 0);
@@ -35,24 +33,24 @@ add_task(async function() {
       }
     );
   });
 
   // Finds the div in the red box.
   scrollPromise = remote ?
     BrowserTestUtils.waitForContentEvent(gBrowser.selectedBrowser, "scroll") :
     BrowserTestUtils.waitForEvent(gBrowser, "scroll");
-  EventUtils.synthesizeKey("g", { accelKey: true });
+  EventUtils.synthesizeKey("g", {accelKey: true});
   await scrollPromise;
 
   await ContentTask.spawn(gBrowser.selectedBrowser, null, async function() {
     Assert.ok(content.document.getElementById("s").getBoundingClientRect().left >= 0,
       "scroll should include find result");
   });
 
   // clear the find bar
-  EventUtils.synthesizeKey("a", { accelKey: true });
-  EventUtils.synthesizeKey("VK_DELETE", { });
+  EventUtils.synthesizeKey("a", {accelKey: true});
+  EventUtils.synthesizeKey("KEY_Delete");
 
   gFindBar.close();
   gBrowser.removeCurrentTab();
 });
 

--- a/browser/base/content/test/general/browser_zbug569342.js
+++ b/browser/base/content/test/general/browser_zbug569342.js
@@ -36,29 +36,29 @@ var urls = [
 
 function nextTest() {
   let url = urls.shift();
   if (url) {
     testFindDisabled(url, nextTest);
   } else {
     // Make sure the find bar is re-enabled after disabled page is closed.
     testFindEnabled("about:blank", function() {
-      EventUtils.synthesizeKey("VK_ESCAPE", { });
+      EventUtils.synthesizeKey("KEY_Escape");
       ok(gFindBar.hidden, "Find bar should now be hidden");
       finish();
     });
   }
 }
 
 function testFindDisabled(url, cb) {
   load(url, function() {
     ok(gFindBar.hidden, "Find bar should not be visible");
     EventUtils.synthesizeKey("/", {}, gTab.linkedBrowser.contentWindow);
     ok(gFindBar.hidden, "Find bar should not be visible");
-    EventUtils.synthesizeKey("f", { accelKey: true });
+    EventUtils.synthesizeKey("f", {accelKey: true});
     ok(gFindBar.hidden, "Find bar should not be visible");
     ok(document.getElementById("cmd_find").getAttribute("disabled"),
        "Find command should be disabled");
 
     gBrowser.removeTab(gTab);
     cb();
   });
 }
@@ -66,15 +66,15 @@ function testFindDisabled(url, cb) {
 function testFindEnabled(url, cb) {
   load(url, function() {
     ok(!document.getElementById("cmd_find").getAttribute("disabled"),
        "Find command should not be disabled");
 
     // Open Find bar and then close it.
     EventUtils.synthesizeKey("f", { accelKey: true });
     ok(!gFindBar.hidden, "Find bar should be visible again");
-    EventUtils.synthesizeKey("VK_ESCAPE", { });
+    EventUtils.synthesizeKey("KEY_Escape");
     ok(gFindBar.hidden, "Find bar should now be hidden");
 
     gBrowser.removeTab(gTab);
     cb();
   });
 }

--- a/browser/base/content/test/general/contentSearchUI.js
+++ b/browser/base/content/test/general/contentSearchUI.js
@@ -28,17 +28,17 @@ var messageHandlers = {
         content.removeEventListener("ContentSearchService", listener);
         ack("init");
       }
     });
   },
 
   key(arg) {
     let keyName = typeof(arg) == "string" ? arg : arg.key;
-    content.synthesizeKey(keyName, arg.modifiers || {});
+    content.synthesizeKey(keyName, arg.modifiers);
     let wait = arg.waitForSuggestions ? waitForSuggestions : cb => cb();
     wait(ack.bind(null, "key"));
   },
 
   startComposition(arg) {
     content.synthesizeComposition({ type: "compositionstart", data: "" });
     ack("startComposition");
   },
@@ -138,19 +138,19 @@ var messageHandlers = {
     ack("removeLastOneOff");
   },
 
   reset() {
     // Reset both the input and suggestions by select all + delete. If there was
     // no text entered, this won't have any effect, so also escape to ensure the
     // suggestions table is closed.
     gController.input.focus();
-    content.synthesizeKey("a", { accelKey: true });
-    content.synthesizeKey("VK_DELETE", {});
-    content.synthesizeKey("VK_ESCAPE", {});
+    content.synthesizeKey("a", {accelKey: true});
+    content.synthesizeKey("KEY_Delete");
+    content.synthesizeKey("KEY_Escape");
     ack("reset");
   },
 };
 
 function ack(aType, aData) {
   sendAsyncMessage(TEST_MSG, { type: aType, data: aData || currentState() });
 }
 

--- a/browser/base/content/test/newtab/browser_newtab_focus.js
+++ b/browser/base/content/test/newtab/browser_newtab_focus.js
@@ -45,17 +45,17 @@ add_task(async function() {
 });
 
 /**
  * Focus the urlbar and count how many focus stops to return again to the urlbar.
  */
 function countFocus(aExpectedCount) {
   let focusCount = 0;
   do {
-    EventUtils.synthesizeKey("VK_TAB", {});
+    EventUtils.synthesizeKey("KEY_Tab");
     if (document.activeElement == gBrowser.selectedBrowser) {
       focusCount++;
     }
   } while (document.activeElement != gURLBar.inputField);
   ok(focusCount == aExpectedCount || focusCount == (aExpectedCount + 1),
      "Validate focus count in the new tab page.");
 }
 

--- a/browser/base/content/test/newtab/browser_newtab_search.js
+++ b/browser/base/content/test/newtab/browser_newtab_search.js
@@ -151,26 +151,26 @@ add_task(async function() {
     observer.observe(input, {
       attributes: true,
       attributeFilter: ["aria-expanded"],
     });
   });
 
   let suggestionsPromise = promiseSearchEvents(["Suggestions"]);
 
-  EventUtils.synthesizeKey("x", {});
+  EventUtils.sendString("x");
 
   // Wait for the search suggestions to become visible and for the Suggestions
   // message.
   await suggestionsOpenPromise;
   await suggestionsPromise;
 
   // Empty the search input, causing the suggestions to be hidden.
-  EventUtils.synthesizeKey("a", { accelKey: true });
-  EventUtils.synthesizeKey("VK_DELETE", {});
+  EventUtils.synthesizeKey("a", {accelKey: true});
+  EventUtils.synthesizeKey("KEY_Delete");
 
   await ContentTask.spawn(gBrowser.selectedBrowser, {}, async function() {
     Assert.ok(content.document.getElementById("searchSuggestionTable").hidden,
       "Search suggestion table hidden");
   });
 
   // Done.  Revert the current engine and remove the new engines.
   searchEventsPromise = promiseSearchEvents(["CurrentEngine"]);

--- a/browser/base/content/test/permissions/browser_reservedkey.js
+++ b/browser/base/content/test/permissions/browser_reservedkey.js
@@ -12,32 +12,28 @@ add_task(async function test_reserved_sh
   let container = document.createElement("box");
   container.unsafeSetInnerHTML(keyset);
   document.documentElement.appendChild(container);
   /* eslint-enable no-unsanitized/property */
 
   const pageUrl = "data:text/html,<body onload='document.body.firstChild.focus();'><div onkeydown='event.preventDefault();' tabindex=0>Test</div></body>";
   let tab = await BrowserTestUtils.openNewForegroundTab(gBrowser, pageUrl);
 
-  EventUtils.synthesizeKey("O", { shiftKey: true });
-  EventUtils.synthesizeKey("P", { shiftKey: true });
-  EventUtils.synthesizeKey("Q", { shiftKey: true });
+  EventUtils.sendString("OPQ");
 
   is(document.getElementById("kt_reserved").getAttribute("count"), "1", "reserved='true' with preference off");
   is(document.getElementById("kt_notreserved").getAttribute("count"), "0", "reserved='false' with preference off");
   is(document.getElementById("kt_reserveddefault").getAttribute("count"), "0", "default reserved with preference off");
 
   // Now try with reserved shortcut key handling enabled.
   await new Promise(resolve => {
     SpecialPowers.pushPrefEnv({"set": [["permissions.default.shortcuts", 2]]}, resolve);
   });
 
-  EventUtils.synthesizeKey("O", { shiftKey: true });
-  EventUtils.synthesizeKey("P", { shiftKey: true });
-  EventUtils.synthesizeKey("Q", { shiftKey: true });
+  EventUtils.sendString("OPQ");
 
   is(document.getElementById("kt_reserved").getAttribute("count"), "2", "reserved='true' with preference on");
   is(document.getElementById("kt_notreserved").getAttribute("count"), "0", "reserved='false' with preference on");
   is(document.getElementById("kt_reserveddefault").getAttribute("count"), "1", "default reserved with preference on");
 
   document.documentElement.removeChild(container);
 
   await BrowserTestUtils.removeTab(tab);
@@ -51,38 +47,38 @@ if (!navigator.platform.includes("Mac"))
     });
 
     const uri = "data:text/html,<body onkeydown='if (event.key == \"H\" || event.key == \"F10\") event.preventDefault();'>";
     let tab1 = await BrowserTestUtils.openNewForegroundTab(gBrowser, uri);
 
     // Pressing Alt+H should open the Help menu.
     let helpPopup = document.getElementById("menu_HelpPopup");
     let popupShown = BrowserTestUtils.waitForEvent(helpPopup, "popupshown");
-    EventUtils.synthesizeKey("VK_ALT", { type: "keydown" });
-    EventUtils.synthesizeKey("H", { altKey: true });
-    EventUtils.synthesizeKey("VK_ALT", { type: "keyup" });
+    EventUtils.synthesizeKey("KEY_Alt", {type: "keydown"});
+    EventUtils.synthesizeKey("h", {altKey: true});
+    EventUtils.synthesizeKey("KEY_Alt", {type: "keyup"});
     await popupShown;
 
     ok(true, "Help menu opened");
 
     let popupHidden = BrowserTestUtils.waitForEvent(helpPopup, "popuphidden");
     helpPopup.hidePopup();
     await popupHidden;
 
     // Pressing F10 should focus the menubar. On Linux, the file menu should open, but on Windows,
     // pressing Down will open the file menu.
     let menubar = document.getElementById("main-menubar");
     let menubarActive = BrowserTestUtils.waitForEvent(menubar, "DOMMenuBarActive");
-    EventUtils.sendKey("F10");
+    EventUtils.synthesizeKey("KEY_F10");
     await menubarActive;
 
     let filePopup = document.getElementById("menu_FilePopup");
     popupShown = BrowserTestUtils.waitForEvent(filePopup, "popupshown");
     if (navigator.platform.includes("Win")) {
-      EventUtils.synthesizeKey("KEY_ArrowDown", {});
+      EventUtils.synthesizeKey("KEY_ArrowDown");
     }
     await popupShown;
 
     ok(true, "File menu opened");
 
     popupHidden = BrowserTestUtils.waitForEvent(filePopup, "popuphidden");
     filePopup.hidePopup();
     await popupHidden;

--- a/browser/base/content/test/popupNotifications/browser_popupNotification_keyboard.js
+++ b/browser/base/content/test/popupNotifications/browser_popupNotification_keyboard.js
@@ -18,17 +18,17 @@ var tests = [
   { id: "Test#1",
     run() {
       this.notifyObj = new BasicNotification(this.id);
       this.notifyObj.options.persistent = true;
       showNotification(this.notifyObj);
     },
     onShown(popup) {
       checkPopup(popup, this.notifyObj);
-      EventUtils.synthesizeKey("VK_ESCAPE", {});
+      EventUtils.synthesizeKey("KEY_Escape");
     },
     onHidden(popup) {
       ok(!this.notifyObj.mainActionClicked, "mainAction was not clicked");
       ok(this.notifyObj.secondaryActionClicked, "secondaryAction was clicked");
       ok(!this.notifyObj.dismissalCallbackTriggered, "dismissal callback wasn't triggered");
       ok(this.notifyObj.removedCallbackTriggered, "removed callback triggered");
     }
   },
@@ -36,17 +36,17 @@ var tests = [
   { id: "Test#2",
     async run() {
       await waitForWindowReadyForPopupNotifications(window);
       this.notifyObj = new BasicNotification(this.id);
       this.notification = showNotification(this.notifyObj);
     },
     onShown(popup) {
       checkPopup(popup, this.notifyObj);
-      EventUtils.synthesizeKey("VK_ESCAPE", {});
+      EventUtils.synthesizeKey("KEY_Escape");
     },
     onHidden(popup) {
       ok(!this.notifyObj.mainActionClicked, "mainAction was not clicked");
       ok(!this.notifyObj.secondaryActionClicked, "secondaryAction was not clicked");
       ok(this.notifyObj.dismissalCallbackTriggered, "dismissal callback triggered");
       ok(!this.notifyObj.removedCallbackTriggered, "removed callback was not triggered");
       this.notification.remove();
     }
@@ -61,17 +61,17 @@ var tests = [
       });
       this.notification = showNotification(this.notifyObj);
     },
     onShown(popup) {
       checkPopup(popup, this.notifyObj);
       let anchor = document.getElementById(this.notifyObj.anchorID);
       anchor.focus();
       is(document.activeElement, anchor);
-      EventUtils.synthesizeKey(" ", {});
+      EventUtils.sendString(" ");
       is(document.activeElement, popup.childNodes[0].closebutton);
       this.notification.remove();
     },
     onHidden(popup) { }
   },
   // Test that you can switch between active notifications with the space key
   // and that the notification is focused on selection.
   { id: "Test#4",
@@ -103,28 +103,28 @@ var tests = [
       // Make sure notification 2 is visible
       checkPopup(popup, notifyObj2);
 
       // Activate the anchor for notification 1 and wait until it's shown.
       let anchor = document.getElementById(notifyObj1.anchorID);
       anchor.focus();
       is(document.activeElement, anchor);
       opened = waitForNotificationPanel();
-      EventUtils.synthesizeKey(" ", {});
+      EventUtils.sendString(" ");
       popup = await opened;
       checkPopup(popup, notifyObj1);
 
       is(document.activeElement, popup.childNodes[0].checkbox);
 
       // Activate the anchor for notification 2 and wait until it's shown.
       anchor = document.getElementById(notifyObj2.anchorID);
       anchor.focus();
       is(document.activeElement, anchor);
       opened = waitForNotificationPanel();
-      EventUtils.synthesizeKey(" ", {});
+      EventUtils.sendString(" ");
       popup = await opened;
       checkPopup(popup, notifyObj2);
 
       is(document.activeElement, popup.childNodes[0].closebutton);
 
       notification1.remove();
       notification2.remove();
       goNext();
@@ -142,17 +142,17 @@ var tests = [
     },
     onShown(popup) {
       checkPopup(popup, this.notifyObj);
 
       // Initial focus on open is null because a panel itself
       // can not be focused, next tab focus will be inside the panel.
       is(Services.focus.focusedElement, null);
 
-      EventUtils.synthesizeKey("VK_TAB", {});
+      EventUtils.synthesizeKey("KEY_Tab");
       is(Services.focus.focusedElement, popup.childNodes[0].closebutton);
       dismissNotification(popup);
     },
     async onHidden() {
       // Focus the urlbar to check that it stays focused.
       gURLBar.focus();
 
       // Show another notification and make sure it's not autofocused.

--- a/browser/base/content/test/popupNotifications/browser_popupNotification_no_anchors.js
+++ b/browser/base/content/test/popupNotifications/browser_popupNotification_no_anchors.js
@@ -115,41 +115,41 @@ var tests = [
         this.notification = showNotification(this.notifyObj);
         await shown;
 
         checkPopup(PopupNotifications.panel, this.notifyObj);
 
         // Typing in the location bar should hide the notification.
         let hidden = waitForNotificationPanelHidden();
         gURLBar.select();
-        EventUtils.synthesizeKey("*", {});
+        EventUtils.sendString("*");
         await hidden;
 
         is(document.getElementById("geo-notification-icon").boxObject.width, 0,
            "geo anchor shouldn't be visible");
 
         // Moving focus to the next control should show the notifications again,
         // anchored to the identity icon. We clear the URL bar before moving the
         // focus so that the awesomebar popup doesn't get in the way.
         shown = waitForNotificationPanel();
-        EventUtils.synthesizeKey("VK_BACK_SPACE", {});
-        EventUtils.synthesizeKey("VK_TAB", {});
+        EventUtils.synthesizeKey("KEY_Backspace");
+        EventUtils.synthesizeKey("KEY_Tab");
         await shown;
 
         is(PopupNotifications.panel.anchorNode.id, "identity-icon",
            "notification anchored to identity icon");
 
         // Moving focus to the location bar should hide the notification again.
         hidden = waitForNotificationPanelHidden();
-        EventUtils.synthesizeKey("VK_TAB", { shiftKey: true });
+        EventUtils.synthesizeKey("KEY_Tab", {shiftKey: true});
         await hidden;
 
         // Reverting the URL should show the notification again.
         shown = waitForNotificationPanel();
-        EventUtils.synthesizeKey("VK_ESCAPE", {});
+        EventUtils.synthesizeKey("KEY_Escape");
         await shown;
 
         checkPopup(PopupNotifications.panel, this.notifyObj);
 
         hidden = waitForNotificationPanelHidden();
         this.notification.remove();
         await hidden;
       }
@@ -158,30 +158,30 @@ var tests = [
   },
   // Test that popupnotifications triggered while editing the URL in the
   // location bar are only shown later when the URL is reverted.
   { id: "Test#5",
     async run() {
       for (let persistent of [false, true]) {
         // Start editing the URL, ensuring that the awesomebar popup is hidden.
         gURLBar.select();
-        EventUtils.synthesizeKey("*", {});
-        EventUtils.synthesizeKey("VK_BACK_SPACE", {});
+        EventUtils.sendString("*");
+        EventUtils.synthesizeKey("KEY_Backspace");
 
         // Trying to show a notification should display nothing.
         let notShowing = promiseTopicObserved("PopupNotifications-updateNotShowing");
         this.notifyObj = new BasicNotification(this.id);
         this.notifyObj.anchorID = "geo-notification-icon";
         this.notifyObj.addOptions({ persistent });
         this.notification = showNotification(this.notifyObj);
         await notShowing;
 
         // Reverting the URL should show the notification.
         let shown = waitForNotificationPanel();
-        EventUtils.synthesizeKey("VK_ESCAPE", {});
+        EventUtils.synthesizeKey("KEY_Escape");
         await shown;
 
         checkPopup(PopupNotifications.panel, this.notifyObj);
 
         let hidden = waitForNotificationPanelHidden();
         this.notification.remove();
         await hidden;
       }
@@ -205,17 +205,17 @@ var tests = [
       // Switching to a new tab should hide the notification.
       let hidden = waitForNotificationPanelHidden();
       this.oldSelectedTab = gBrowser.selectedTab;
       await BrowserTestUtils.openNewForegroundTab(gBrowser, "http://example.com/");
       await hidden;
 
       // Start editing the URL.
       gURLBar.select();
-      EventUtils.synthesizeKey("*", {});
+      EventUtils.sendString("*");
 
       // Switching to the old tab should show the notification again.
       shown = waitForNotificationPanel();
       gBrowser.removeTab(gBrowser.selectedTab);
       gBrowser.selectedTab = this.oldSelectedTab;
       await shown;
 
       checkPopup(PopupNotifications.panel, this.notifyObj);

--- a/browser/base/content/test/popupNotifications/head.js
+++ b/browser/base/content/test/popupNotifications/head.js
@@ -118,17 +118,17 @@ function showNotification(notifyObj) {
                                  notifyObj.anchorID,
                                  notifyObj.mainAction,
                                  notifyObj.secondaryActions,
                                  notifyObj.options);
 }
 
 function dismissNotification(popup) {
   info("Dismissing notification " + popup.childNodes[0].id);
-  executeSoon(() => EventUtils.synthesizeKey("VK_ESCAPE", {}));
+  executeSoon(() => EventUtils.synthesizeKey("KEY_Escape"));
 }
 
 function BasicNotification(testId) {
   this.browser = gBrowser.selectedBrowser;
   this.id = "test-notification-" + testId;
   this.message = "This is popup notification for " + testId;
   this.anchorID = null;
   this.mainAction = {
@@ -304,18 +304,18 @@ function triggerSecondaryCommand(popup, 
   // Extra secondary actions appear in a menu.
   notification.secondaryButton.nextSibling.nextSibling.focus();
 
   popup.addEventListener("popupshown", function() {
     info("Command popup open for notification " + notification.id);
     // Press down until the desired command is selected. Decrease index by one
     // since the secondary action was handled above.
     for (let i = 0; i <= index - 1; i++) {
-      EventUtils.synthesizeKey("VK_DOWN", {});
+      EventUtils.synthesizeKey("KEY_ArrowDown");
     }
     // Activate
-    EventUtils.synthesizeKey("VK_RETURN", {});
+    EventUtils.synthesizeKey("KEY_Enter");
   }, {once: true});
 
   // One down event to open the popup
   info("Open the popup to trigger secondary command for notification " + notification.id);
-  EventUtils.synthesizeKey("VK_DOWN", { altKey: !navigator.platform.includes("Mac") });
+  EventUtils.synthesizeKey("KEY_ArrowDown", {altKey: !navigator.platform.includes("Mac")});
 }