Provide custom messages for the no-restricted-globals ESLint rule, and refactor the .eslintrc files (PR 9868 follow-up)

Without providing useful (custom) error messages for the `no-restricted-globals` rule, see https://eslint.org/docs/rules/no-restricted-globals, it's quite likely that the rule will be incorrectly disabled rather than the required globals being imported as intended.

To reduced duplication of the `no-restricted-globals` rule in multiple `.eslintrc` files, it's instead moved to the top-level `.eslintrc` file and disabled as needed on a folder/file basis outside of `/src` and `/web`.

.eslintrc

@@ -100,7 +100,20 @@
     "no-catch-shadow": "error",
     "no-delete-var": "error",
     "no-label-var": "error",
-    "no-restricted-globals": "off",
+    "no-restricted-globals": ["error",
+      {
+        "name": "ReadableStream",
+        "message": "Import it from `src/shared/util.js` or `pdfjsLib` instead; outside of the `/src` and `/web` folders, the rule may be disabled as needed. ",
+      },
+      {
+        "name": "URL",
+        "message": "Import it from `src/shared/util.js` or `pdfjsLib` instead; outside of the `/src` and `/web` folders, the rule may be disabled as needed. ",
+      },
+      {
+        "name": "WritableStream",
+        "message": "Import it from `src/shared/util.js` or `pdfjsLib` instead; outside of the `/src` and `/web` folders, the rule may be disabled as needed. ",
+      },
+    ],
     "no-shadow-restricted-names": "error",
     "no-shadow": "off",
     "no-undef-init": "error",

extensions/.eslintrc

@@ -0,0 +1,9 @@
+{
+  "extends": [
+    ../.eslintrc
+  ],
+
+  "rules": {
+    "no-restricted-globals": "off",
+  },
+}

external/.eslintrc

@@ -9,7 +9,7 @@
 
   "rules": {
     "mozilla/use-includes-instead-of-indexOf": "off",
-
     "object-shorthand": "off",
+    "no-restricted-globals": "off",
   },
 }

src/.eslintrc

@@ -1,14 +0,0 @@
-{
-  "extends": [
-    ../.eslintrc
-  ],
-
-  "rules": {
-    // Variables
-    "no-restricted-globals": ["error",
-      "ReadableStream",
-      "URL",
-      "WritableStream",
-    ],
-  },
-}

systemjs.config.js

@@ -12,6 +12,7 @@
  * See the License for the specific language governing permissions and
  * limitations under the License.
  */
+/* eslint-disable no-restricted-globals */
 
 'use strict';
 

test/.eslintrc

@@ -7,4 +7,8 @@
     "node": true,
     "jasmine": true,
   },
+
+  "rules": {
+    "no-restricted-globals": "off",
+  },
 }

web/.eslintrc

@@ -4,13 +4,6 @@
   ],
 
   "rules": {
-    // Variables
-    "no-restricted-globals": ["error",
-      "ReadableStream",
-      "URL",
-      "WritableStream",
-    ],
-
     // ECMAScript 6
     "no-var": "error",
   },