[turbofan] Run everything after representation selection concurrently.

src/x64/macro-assembler-x64.h

Index: src/x64/macro-assembler-x64.h
diff --git a/src/x64/macro-assembler-x64.h b/src/x64/macro-assembler-x64.h
index 5b9be09d45b14ac365bdf4e7956e3db95215f94b..223e4647a11d39ba38f8e81c8cb2cc9062aa34eb 100644
--- a/src/x64/macro-assembler-x64.h
+++ b/src/x64/macro-assembler-x64.h
@@ -21,6 +21,7 @@ const Register kReturnRegister1 = {Register::kCode_rdx};
 const Register kReturnRegister2 = {Register::kCode_r8};
 const Register kJSFunctionRegister = {Register::kCode_rdi};
 const Register kContextRegister = {Register::kCode_rsi};
+const Register kAllocateSizeRegister = {Register::kCode_rdx};
 const Register kInterpreterAccumulatorRegister = {Register::kCode_rax};
 const Register kInterpreterBytecodeOffsetRegister = {Register::kCode_r12};
 const Register kInterpreterBytecodeArrayRegister = {Register::kCode_r14};