Reviewed by Oliver Hunt.

        Fix armv7 JIT build issues.

        Unfortunate the arm compiler does not like the use of offsetof on JITStackFrame (since it now contains non POD types),
        and the FIELD_OFFSET macro does not appear constantish enough for it to be happy with its use in COMPILE_ASSERT macros.

        * Replace offsetofs with FIELD_OFFSETs (safe on C++ objects).
        * Move COMPILE_ASSERTs defending layout of JITStackFrame structure on armv7 into JITThunks constructor.

        * jit/JIT.cpp:
        * jit/JIT.h:
        * jit/JITInlineMethods.h:
        (JSC::JIT::restoreArgumentReference):
        * jit/JITOpcodes.cpp:
        (JSC::JIT::emit_op_catch):
        * jit/JITStubs.cpp:
        (JSC::JITThunks::JITThunks):



git-svn-id: http://svn.webkit.org/repository/webkit/trunk@44884 268f45cc-cd09-0410-ab3c-d52691b4dbfc