repl: removing the buggy trimWhitespace function

As it is, the trimWhitespace function will not remove the white sapce
characters at the end of the string, as the greedy capturing group .+
captures everything till end of the string, leaving \s* with nothing.
This patch removes the function and uses a proper RegEx which will
match all the whitespace characters at the beginning and ending of the
string and replaces the matched whitespace characters with empty string

lib/repl.js

@@ -272,7 +272,7 @@ function REPLServer(prompt,
     if (self._inTemplateLiteral) {
       self._inTemplateLiteral = false;
     } else {
-      cmd = trimWhitespace(cmd);
+      cmd = cmd.trim();
     }
 
     // Check to see if a REPL keyword was used. If it returns true,
@@ -944,18 +944,6 @@ function defineDefaultCommands(repl) {
   });
 }
 
-
-function trimWhitespace(cmd) {
-  const trimmer = /^\s*(.+)\s*$/m;
-  var matches = trimmer.exec(cmd);
-
-  if (matches && matches.length === 2) {
-    return matches[1];
-  }
-  return '';
-}
-
-
 function regexpEscape(s) {
   return s.replace(/[-[\]{}()*+?.,\\^$|#\s]/g, '\\$&');
 }

test/fixtures/repl-load.js

@@ -0,0 +1 @@
+module.exports = 'repl';

test/parallel/test-repl.js

@@ -189,7 +189,13 @@ function error_test() {
     { client: client_unix, send: 'url.format("http://google.com")',
       expect: 'http://google.com/' },
     { client: client_unix, send: 'var path = 42; path',
-      expect: '42' }
+      expect: '42' },
+    // making sure that the fixed trim logic works fine
+    { client: client_unix, send: '    \t  .break \t \t  ',
+      expect: prompt_unix },
+    { client: client_unix, send: '.load ' +
+              require('path').join(common.fixturesDir, 'repl-load.js     \t   '),
+      expect: prompt_unix + '\'repl\'\n' + prompt_unix },
   ]);
 }