Upgrade es6 -> es2021

This uses the recommended target for node 16 in tsconfig/bases.

Fixes #4706

.eslintrc.json

@@ -1,7 +1,7 @@
 {
   "env": {
     "browser": true,
-    "es6": true,
+    "es2021": true,
     "node": true
   },
   "parser": "@typescript-eslint/parser",

.eslintrc.json.typings

@@ -1,7 +1,7 @@
 {
   "env": {
     "browser": true,
-    "es6": true,
+    "es2021": true,
     "node": true
   },
   "parser": "@typescript-eslint/parser",

addons/xterm-addon-attach/src/tsconfig.json

@@ -1,7 +1,7 @@
 {
   "compilerOptions": {
     "module": "commonjs",
-    "target": "es2015",
+    "target": "es2021",
     "lib": [
       "dom",
       "es2015"

addons/xterm-addon-attach/test/tsconfig.json

@@ -1,7 +1,7 @@
 {
   "compilerOptions": {
     "module": "commonjs",
-    "target": "es2015",
+    "target": "es2021",
     "lib": [
       "es2015"
     ],

addons/xterm-addon-canvas/src/tsconfig.json

@@ -1,10 +1,10 @@
 {
   "compilerOptions": {
     "module": "commonjs",
-    "target": "es2015",
+    "target": "es2021",
     "lib": [
       "dom",
-      "es6"
+      "es2021"
     ],
     "rootDir": ".",
     "outDir": "../out",

addons/xterm-addon-fit/src/tsconfig.json

@@ -1,7 +1,7 @@
 {
   "compilerOptions": {
     "module": "commonjs",
-    "target": "es2015",
+    "target": "es2021",
     "lib": [
       "dom",
       "es2015"

addons/xterm-addon-fit/test/tsconfig.json

@@ -1,7 +1,7 @@
 {
   "compilerOptions": {
     "module": "commonjs",
-    "target": "es2015",
+    "target": "es2021",
     "lib": [
       "es2015"
     ],

addons/xterm-addon-search/src/tsconfig.json

@@ -1,10 +1,10 @@
 {
   "compilerOptions": {
     "module": "commonjs",
-    "target": "es2015",
+    "target": "es2021",
     "lib": [
       "dom",
-      "es6",
+      "es2021",
     ],
     "rootDir": ".",
     "outDir": "../out",

addons/xterm-addon-search/test/tsconfig.json

@@ -1,9 +1,9 @@
 {
   "compilerOptions": {
     "module": "commonjs",
-    "target": "es2015",
+    "target": "es2021",
     "lib": [
-      "es6",
+      "es2021",
     ],
     "rootDir": ".",
     "outDir": "../out-test",

addons/xterm-addon-serialize/benchmark/tsconfig.json

@@ -1,11 +1,14 @@
 {
   "compilerOptions": {
-    "lib": ["dom", "es6"],
+    "lib": [
+      "dom",
+      "es2021"
+    ],
     "outDir": "../out-benchmark",
     "types": ["../../../node_modules/@types/node"],
     "moduleResolution": "node",
     "strict": false,
-    "target": "es2015",
+    "target": "es2021",
     "module": "commonjs",
     "baseUrl": ".",
     "paths": {

addons/xterm-addon-serialize/src/tsconfig.json

@@ -1,7 +1,7 @@
 {
   "compilerOptions": {
     "module": "commonjs",
-    "target": "es2015",
+    "target": "es2021",
     "lib": [
       "dom",
       "es2015"

addons/xterm-addon-serialize/test/tsconfig.json

@@ -1,7 +1,7 @@
 {
   "compilerOptions": {
     "module": "commonjs",
-    "target": "es2015",
+    "target": "es2021",
     "lib": [
       "es2015"
     ],

addons/xterm-addon-unicode11/src/tsconfig.json

@@ -1,7 +1,7 @@
 {
   "compilerOptions": {
     "module": "commonjs",
-    "target": "es2015",
+    "target": "es2021",
     "lib": [
       "dom",
       "es2015"

addons/xterm-addon-unicode11/test/tsconfig.json

@@ -1,7 +1,7 @@
 {
   "compilerOptions": {
     "module": "commonjs",
-    "target": "es2015",
+    "target": "es2021",
     "lib": [
       "dom",
       "es2015"

addons/xterm-addon-web-links/src/tsconfig.json

@@ -1,7 +1,7 @@
 {
   "compilerOptions": {
     "module": "commonjs",
-    "target": "es2015",
+    "target": "es2021",
     "lib": [
       "dom",
       "es2015"

addons/xterm-addon-web-links/test/tsconfig.json

@@ -1,7 +1,7 @@
 {
   "compilerOptions": {
     "module": "commonjs",
-    "target": "es2015",
+    "target": "es2021",
     "lib": [
       "es2015"
     ],

addons/xterm-addon-webgl/src/tsconfig.json

@@ -1,10 +1,10 @@
 {
   "compilerOptions": {
     "module": "commonjs",
-    "target": "es2015",
+    "target": "es2021",
     "lib": [
       "dom",
-      "es6"
+      "es2021"
     ],
     "rootDir": ".",
     "outDir": "../out",

addons/xterm-addon-webgl/test/tsconfig.json

@@ -1,9 +1,9 @@
 {
   "compilerOptions": {
     "module": "commonjs",
-    "target": "es2015",
+    "target": "es2021",
     "lib": [
-      "es6",
+      "es2021",
     ],
     "rootDir": ".",
     "outDir": "../out-test",

demo/tsconfig.json

@@ -1,7 +1,7 @@
 {
   "compilerOptions": {
     "module": "commonjs",
-    "target": "es2015",
+    "target": "es2021",
     "rootDir": ".",
     "sourceMap": true,
     "baseUrl": ".",

src/browser/tsconfig.json

@@ -3,8 +3,7 @@
   "compilerOptions": {
     "lib": [
       "dom",
-      "es2015",
-      "es2016.Array.Include"
+      "es2021"
     ],
     "outDir": "../../out",
     "types": [