fix: allow legacyiterable and implements to be identifiers

.eslintrc.json

@@ -9,6 +9,7 @@
     },
     "extends": "eslint:recommended",
     "rules": {
+        "no-console": "error",
         "no-constant-condition": ["error", { "checkLoops": false }],
         "no-eval": "error",
         "no-implied-eval": "error",

lib/productions/extended-attributes.js

@@ -108,7 +108,6 @@ export class ExtendedAttributes extends ArrayBase {
 
   *validate(defs) {
     for (const extAttr of this) {
-      console.log(extAttr);
       yield* extAttr.validate(defs);
     }
   }

lib/tokeniser.js

@@ -55,8 +55,6 @@ const nonRegexTerminals = [
   "double",
   "false",
   "float",
-  "implements",
-  "legacyiterable",
   "long",
   "mixin",
   "null",

test/invalid/baseline/legacyiterable.txt

@@ -1,3 +1,3 @@
 Syntax error at line 2 in legacyiterable.webidl, since `interface LegacyIterable`:
   legacyiterable<long>;
-  ^ Missing return type
+                ^ Unsupported generic type legacyiterable

test/syntax/baseline/obsolete-keywords.json

@@ -0,0 +1,46 @@
+[
+    {
+        "type": "interface",
+        "name": "Keywords",
+        "inheritance": null,
+        "members": [
+            {
+                "type": "operation",
+                "name": "implements",
+                "idlType": {
+                    "type": "return-type",
+                    "extAttrs": [],
+                    "generic": "",
+                    "nullable": false,
+                    "union": false,
+                    "idlType": "void"
+                },
+                "arguments": [],
+                "extAttrs": [],
+                "special": ""
+            },
+            {
+                "type": "operation",
+                "name": "legacyiterable",
+                "idlType": {
+                    "type": "return-type",
+                    "extAttrs": [],
+                    "generic": "",
+                    "nullable": false,
+                    "union": false,
+                    "idlType": "void"
+                },
+                "arguments": [],
+                "extAttrs": [],
+                "special": ""
+            }
+        ],
+        "extAttrs": [],
+        "partial": false
+    },
+    {
+        "type": "eof",
+        "value": "",
+        "trivia": "\n"
+    }
+]

test/syntax/idl/obsolete-keywords.webidl

@@ -0,0 +1,6 @@
+// Keywords that have been removed from the spec
+// can be used as an identifier
+interface Keywords {
+  void implements();
+  void legacyiterable();
+};