Highlight breaks with constants

[alexr00]

From @AlexTalker in microsoft/vscode#81309

• VSCode Version: 1.38.1
• OS Version: Windows_NT x64 10.0.17763

Steps to Reproduce:

1. Create a perl module like this:

use v5.10;
use strict;
use warning;

use constant FOO => 42;

my $x = 33;
$x = $x << FOO;

say($x);

2. Notice that after utilization of FOO, color highlight breaks:
   

Does this issue occur when all extensions are disabled?: Yes

The problem seems to be that this regular expression https://github.com/textmate/perl.tmbundle/blob/master/Syntaxes/Perl.plist#L2080 breaks rules of Perl syntax:

The terminating string may be either an identifier (a word), or some quoted text. An unquoted identifier works like double quotes. There may not be a space between the << and the identifier, unless the identifier is explicitly quoted. The terminating string must appear by itself (unquoted and with no surrounding white-space) on the terminating line.

https://perldoc.perl.org/perlop.html#Quote-and-Quote-like-Operators

As it consumes a white-spaces successfully.
I don't know who's to blame here, so I make the issue here and you can if necessary duplicate it to TextMate project.

On huge projects, it is really annoying to break syntax of a large file by simple usage of a constant.