Remove unused data member from Lexer class

Remove unused data member from Lexer class
https://bugs.webkit.org/show_bug.cgi?id=83429

Reviewed by Kentaro Hara.

I noticed that m_delimited was "write-only", so I deleted it.

* parser/Lexer.cpp:
(JSC::Lexer::setCode): Removed code to set m_delimited.
(JSC::Lexer::parseIdentifier): Ditto.
(JSC::Lexer::parseIdentifierSlowCase): Ditto.
(JSC::Lexer::lex): Ditto.
* parser/Lexer.h: Deleted m_delimited.

git-svn-id: https://svn.webkit.org/repository/webkit/trunk@113765 268f45cc-cd09-0410-ab3c-d52691b4dbfc