Use static_cast and other style cleanup in YarrInterpreter.cpp

Use static_cast and other style cleanup in YarrInterpreter.cpp
<http://webkit.org/b/53772>

Reviewed by John Sullivan.

* yarr/YarrInterpreter.cpp:
(JSC::Yarr::Interpreter::InputStream::readChecked): Use
static_cast.
(JSC::Yarr::Interpreter::InputStream::checkInput): Remove
unnecessary else block.
(JSC::Yarr::Interpreter::matchAssertionEOL): Ditto.
(JSC::Yarr::Interpreter::backtrackBackReference): Ditto.
(JSC::Yarr::ByteCompiler::emitDisjunction): Use static_cast.

git-svn-id: http://svn.webkit.org/repository/webkit/trunk@77635 268f45cc-cd09-0410-ab3c-d52691b4dbfc