repl: do not consider `...` as a REPL command

This fix makes ... in REPL to be considered as a javascript construct
rather than a REPL keyword.

Fixes: https://github.com/nodejs/node/issues/14426
PR-URL: https://github.com/nodejs/node/pull/14467
Reviewed-By: Roman Reiss <me@silverwind.io>
Reviewed-By: Anna Henningsen <anna@addaleax.net>
Reviewed-By: Jeremiah Senkpiel <fishrock123@rocketmail.com>

lib/repl.js

@@ -419,7 +419,8 @@ function REPLServer(prompt,
     // Check to see if a REPL keyword was used. If it returns true,
     // display next prompt and return.
     if (trimmedCmd) {
-      if (trimmedCmd.charAt(0) === '.' && isNaN(parseFloat(trimmedCmd))) {
+      if (trimmedCmd.charAt(0) === '.' && trimmedCmd.charAt(1) !== '.' &&
+          isNaN(parseFloat(trimmedCmd))) {
         const matches = trimmedCmd.match(/^\.([^\s]+)\s*(.*)$/);
         const keyword = matches && matches[1];
         const rest = matches && matches[2];

test/parallel/test-repl.js

@@ -414,7 +414,13 @@ function error_test() {
       expect: `${prompt_multiline}'foo \\n'\n${prompt_unix}` },
     // Whitespace is not evaluated.
     { client: client_unix, send: ' \t  \n',
-      expect: prompt_unix }
+      expect: prompt_unix },
+    // Do not parse `...[]` as a REPL keyword
+    { client: client_unix, send: '...[]\n',
+      expect: `${prompt_multiline}` },
+    // bring back the repl to prompt
+    { client: client_unix, send: '.break',
+      expect: `${prompt_unix}` }
   ]);
 }