Incremental mode now works for x64. The only difference

src/ia32/code-stubs-ia32.cc

Index: src/ia32/code-stubs-ia32.cc
===================================================================
--- src/ia32/code-stubs-ia32.cc	(revision 8221)
+++ src/ia32/code-stubs-ia32.cc	(working copy)
@@ -6267,10 +6267,9 @@
     Label dont_need_remembered_set;
 
     __ mov(regs_.scratch0(), Operand(regs_.address(), 0));
-    __ InNewSpace(regs_.scratch0(),
-                  regs_.scratch0(),
-                  zero,
-                  &dont_need_remembered_set);
+    __ JumpIfNotInNewSpace(regs_.scratch0(),
+                           regs_.scratch0(),
+                           &dont_need_remembered_set);
 
     __ CheckPageFlag(regs_.object(),
                      regs_.scratch0(),
@@ -6300,8 +6299,6 @@
 
 void RecordWriteStub::InformIncrementalMarker(MacroAssembler* masm) {
   regs_.SaveCallerSaveRegisters(masm, save_fp_regs_mode_);
-  // TODO(gc) we are assuming that xmm registers are not modified by
-  // the C function we are calling.
   int argument_count = 3;
   __ PrepareCallCFunction(argument_count, regs_.scratch0());
   __ mov(Operand(esp, 0 * kPointerSize), regs_.object());