allocator. 3.6% performance improvement on JavaScript iBench.

        * kjs/internal.cpp:
        (InterpreterImp::mark): Don't mark the empty list.

	For all the methods below I basically lifted the ListImp version
	up to the List method with minor tweaks.

        * kjs/types.cpp:
        (ListIterator::ListIterator):
        (List::List):
        (List::operator=):
        (List::~List):
        (List::mark):
        (List::append):
        (List::prepend):
        (List::appendList):
        (List::prependList):
        (List::removeFirst):
        (List::removeLast):
        (List::remove):
        (List::clear):
        (List::clearInternal):
        (List::copy):
        (List::begin):
        (List::end):
        (List::isEmpty):
        (List::size):
        (List::at):
        (List::operator[]):
        (List::empty):
        (List::erase):
        (List::refAll):
        (List::derefAll):
        (List::swap):
        (List::globalClear):
        * kjs/types.h:


git-svn-id: http://svn.webkit.org/repository/webkit/trunk@2748 268f45cc-cd09-0410-ab3c-d52691b4dbfc