Fix shell heredoc token

A heredoc token cannot contain space. If we don't add this rule, we will
have a wrong coloration when the heredoc is piped into a second command.

FIX: In Shell mode, don't allow spaces in heredoc tokens.

Co-authored-by: Samir ALI CHERIF <samir@cyberwatch.fr>

mode/shell.js

@@ -55,9 +55,9 @@ function tokenBase(stream, state) {
   }
   if (ch == "<") {
     if (stream.match("<<")) return "operator"
-    var heredoc = stream.match(/^<-?\s*['"]?([^'"]*)['"]?/)
+    var heredoc = stream.match(/^<-?\s*(?:['"]([^'"]*)['"]|([^'"\s]*))/)
     if (heredoc) {
-      state.tokens.unshift(tokenHeredoc(heredoc[1]))
+      state.tokens.unshift(tokenHeredoc(heredoc[1] || heredoc[2]))
       return 'string.special'
     }
   }