Reviewed by Oliver Hunt.

Add support for <, <=, ==, ===, and also !.  Add support for all corresponding
bytecode ops, including the not- and -null forms.  Initially add functionally
correct support, we'll revisit the performance.

* dfg/DFGByteCodeParser.cpp:
(JSC::DFG::ByteCodeParser::ByteCodeParser):
(JSC::DFG::ByteCodeParser::constantNull):
(JSC::DFG::ByteCodeParser::parse):
    - Add support for parsing of bytecode opcodes, 
* dfg/DFGJITCodeGenerator.h:
(JSC::DFG::JITCodeGenerator::callOperation):
    - Add new operation call types, return bool values.
* dfg/DFGNode.h:
    - Add new node types.
* dfg/DFGNonSpeculativeJIT.cpp:
(JSC::DFG::NonSpeculativeJIT::compile):
    - Add code generation for new nodes.
* dfg/DFGOperations.cpp:
(JSC::DFG::operationCompareLess):
(JSC::DFG::operationCompareLessEq):
(JSC::DFG::operationCompareEq):
(JSC::DFG::operationCompareStrictEq):
(JSC::DFG::dfgConvertJSValueToBoolean):
* dfg/DFGOperations.h:
    - Add operation callbacks to implement new ops.
* dfg/DFGSpeculativeJIT.cpp:
(JSC::DFG::SpeculativeJIT::compile):
    - Add code generation for new nodes.
* jit/JITOpcodes.cpp:
(JSC::JIT::privateCompileCTIMachineTrampolines):
    - Switched to a simpler <0 check, rather than relying on an internal value in JSImmediate.
* jit/JITPropertyAccess.cpp:
(JSC::JIT::privateCompilePatchGetArrayLength):
    - Switched to a simpler <0 check, rather than relying on an internal value in JSImmediate.
* runtime/JSImmediate.h:
    - Make tag values public, rather than relying on a friend - this matches JSVALUE32_64.



git-svn-id: http://svn.webkit.org/repository/webkit/trunk@83337 268f45cc-cd09-0410-ab3c-d52691b4dbfc