repl: removing the buggy trimWhitespace function

[thefourtheye]

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.

This is a floating fix till #2163 lands

cc @chrisdickinson

[alexlamsl]

Why won't String.prototype.trim() suffice here?

[thefourtheye]

@alexlamsl True, but the other PR I submitted has needs to trim either the start or the end of the string. So I thought this will be consistent.

[silverwind]

LGTM, thought I'd also prefer to use standard .trim(), which is probably faster than your regex.

[Fishrock123]

This is a floating fix till #2163 lands

@silverwind maybe you could also just review #2163? I'd prefer it landed.

[thefourtheye]

@silverwind@alexlamsl PTAL. Working on #2163's review comments.

[silverwind]

LGTM 👍

[Fishrock123]

Closing in favor of #2163 since it's pretty well reviewed.