Reviewed by Darin and Oliver.
        
        Add evaluateToNumber parallel evaluation tree to speed up number operations.
        Make ImmediateNumberNode a subclass of NumberNode.
        Share evaluate logic between evaluate and evaluateToNumber using inline functions
        There is still a lot of improvement to be made here.
        
        SunSpider claims this is a 1.0% speedup overall (nbody 7.9%), base64 slowing 2.0%
        Given the huge win that this prepares us for with simple type inferencing I see the small
        regression in base64 being worth the substantial overall improvement.

        * kjs/grammar.y:
        * kjs/nodes.cpp:
        (KJS::Node::evaluateToNumber):
        (KJS::NumberNode::evaluate):
        (KJS::NumberNode::evaluateToNumber):
        (KJS::StringNode::evaluateToNumber):
        (KJS::LocalVarAccessNode::inlineEvaluate):
        (KJS::LocalVarAccessNode::evaluate):
        (KJS::LocalVarAccessNode::evaluateToNumber):
        (KJS::BracketAccessorNode::inlineEvaluate):
        (KJS::BracketAccessorNode::evaluate):
        (KJS::BracketAccessorNode::evaluateToNumber):
        (KJS::NegateNode::evaluate):
        (KJS::NegateNode::evaluateToNumber):
        (KJS::MultNode::inlineEvaluateToNumber):
        (KJS::MultNode::evaluate):
        (KJS::MultNode::evaluateToNumber):
        (KJS::DivNode::inlineEvaluateToNumber):
        (KJS::DivNode::evaluate):
        (KJS::DivNode::evaluateToNumber):
        (KJS::ModNode::inlineEvaluateToNumber):
        (KJS::ModNode::evaluate):
        (KJS::ModNode::evaluateToNumber):
        (KJS::throwOutOfMemoryErrorToNumber):
        (KJS::addSlowCaseToNumber):
        (KJS::add):
        (KJS::addToNumber):
        (KJS::AddNode::evaluateToNumber):
        (KJS::SubNode::inlineEvaluateToNumber):
        (KJS::SubNode::evaluate):
        (KJS::SubNode::evaluateToNumber):
        (KJS::valueForReadModifyAssignment):
        (KJS::ReadModifyLocalVarNode::evaluate):
        (KJS::ReadModifyResolveNode::evaluate):
        (KJS::ReadModifyDotNode::evaluate):
        (KJS::ReadModifyBracketNode::evaluate):
        * kjs/nodes.h:
        (KJS::Node::):
        (KJS::NumberNode::):
        (KJS::ImmediateNumberNode::):
        (KJS::AddNode::precedence):
        * kjs/nodes2string.cpp:
        (KJS::NumberNode::streamTo):


git-svn-id: http://svn.webkit.org/repository/webkit/trunk@27589 268f45cc-cd09-0410-ab3c-d52691b4dbfc