Reland "Merge cellspace into old pointer space"

src/x64/code-stubs-x64.cc

Index: src/x64/code-stubs-x64.cc
diff --git a/src/x64/code-stubs-x64.cc b/src/x64/code-stubs-x64.cc
index b25cf79ee5ab0118df6b29875345e8ad85600971..401db6b3fbfc6af98c7f0e3eee01997106eb3127 100644
--- a/src/x64/code-stubs-x64.cc
+++ b/src/x64/code-stubs-x64.cc
@@ -2754,6 +2754,12 @@ void InstanceofStub::Generate(MacroAssembler* masm) {
     __ movp(kScratchRegister,
             Operand(kScratchRegister, kOffsetToMapCheckValue));
     __ movp(Operand(kScratchRegister, 0), map);
+
+    __ movp(r8, map);
+    // Scratch points at the cell payload. Calculate the start of the object.
+    __ subp(kScratchRegister, Immediate(Cell::kValueOffset - 1));
+    __ RecordWriteField(kScratchRegister, Cell::kValueOffset, r8, function,
+                        kDontSaveFPRegs, OMIT_REMEMBERED_SET, OMIT_SMI_CHECK);
   }
 
   // Loop through the prototype chain looking for the function prototype.