Reviewed by Maciej Stachowiak.

        Add a new opcode jnlesseq, and optimize its compilation in the JIT using
        techniques similar to what were used to optimize jnless in r43363.

        This gives a 0.7% speedup on SunSpider, particularly on the tests 3d-cube,
        control-flow-recursive, date-format-xparb, and string-base64.

        * bytecode/CodeBlock.cpp:
        (JSC::CodeBlock::dump): Add support for dumping op_jnlesseq.
        * bytecode/Opcode.h: Add op_jnlesseq to the list of opcodes.
        * bytecompiler/BytecodeGenerator.cpp:
        (JSC::BytecodeGenerator::emitJumpIfFalse): Add a peephole optimization
        for op_jnlesseq when emitting lesseq followed by a jump.
        * interpreter/Interpreter.cpp:
        (JSC::Interpreter::privateExecute): Add case for op_jnlesseq.
        * jit/JIT.cpp:
        (JSC::JIT::privateCompileMainPass): Add case for op_jnlesseq.
        (JSC::JIT::privateCompileSlowCases): Add case for op_jnlesseq.
        * jit/JIT.h:
        * jit/JITArithmetic.cpp:
        (JSC::JIT::compileFastArith_op_jnlesseq): Added.
        (JSC::JIT::compileFastArithSlow_op_jnlesseq): Added.
        * jit/JITStubs.cpp:
        (JSC::JITStubs::cti_op_jlesseq): Added.
        * jit/JITStubs.h:


git-svn-id: http://svn.webkit.org/repository/webkit/trunk@43401 268f45cc-cd09-0410-ab3c-d52691b4dbfc