Use Object.assign instead of shallowMerge

.eslintrc

@@ -20,7 +20,6 @@ globals:
   prefs: false
   reportError: true
   getActiveTab: true
-  shallowMerge: true
   t: true
   getCodeMirrorThemes: true
   setupLivePrefs: true

edit.js

@@ -130,7 +130,7 @@ function initCodeMirror() {
 	var isWindowsOS = navigator.appVersion.indexOf("Windows") > 0;
 
 	// default option values
-	shallowMerge(CM.defaults, {
+	Object.assign(CM.defaults, {
 		mode: 'css',
 		lineNumbers: true,
 		lineWrapping: true,
@@ -1591,7 +1591,7 @@ function showCodeMirrorPopup(title, html, options) {
 	var popup = showHelp(title, html);
 	popup.classList.add("big");
 
-	popup.codebox = CodeMirror(popup.querySelector(".contents"), shallowMerge({
+	popup.codebox = CodeMirror(popup.querySelector(".contents"), Object.assign({
 		mode: "css",
 		lineNumbers: true,
 		lineWrapping: true,

messaging.js

@@ -14,7 +14,7 @@ function notifyAllTabs(request) {
 		});
 	});
 	// notify all open popups
-	var reqPopup = shallowMerge({}, request, {method: "updatePopup", reason: request.method});
+	const reqPopup = Object.assign({}, request, {method: 'updatePopup', reason: request.method});
 	chrome.runtime.sendMessage(reqPopup);
 	// notify self: the message no longer is sent to the origin in new Chrome
 	if (typeof applyOnMessage !== 'undefined') {

storage.js

@@ -521,17 +521,6 @@ function deepMerge(target, obj1 /* plus any number of object arguments */) {
 	return target;
 }
 
-function shallowMerge(target, obj1 /* plus any number of object arguments */) {
-	for (var i = 1; i < arguments.length; i++) {
-		var obj = arguments[i];
-		for (var k in obj) {
-			target[k] = obj[k];
-			// hasOwnProperty checking is not needed for our non-OOP stuff
-		}
-	}
-	return target;
-}
-
 function equal(a, b) {
 	if (!a || !b || typeof a != "object" || typeof b != "object") {
 		return a === b;