bug#17262: In Perl mode, TAB zaps EOF marker alignment

[積丹尼 Dan Jacobson]

In Perl mode, TAB zaps EOF marker alignment.
$ cat p.pl
print <<\EOF;
        <ol>
EOF
$ emacs p.pl
now do
C-x h runs the command mark-whole-buffer
TAB (translated from <tab>) runs the command indent-for-tab-command

The result is the EOF is no longer hugging the left margin!
Any following code will be printed out rather than executed, if indeed
the program's syntax is still valid.