[turbofan] Implement the call protocol properly for direct calls.

src/x87/macro-assembler-x87.h

Index: src/x87/macro-assembler-x87.h
diff --git a/src/x87/macro-assembler-x87.h b/src/x87/macro-assembler-x87.h
index 5a1f0cbb15630da71c25e54f4d2b92a679977804..4535f8f9f463e13196c09642f18789e295cef078 100644
--- a/src/x87/macro-assembler-x87.h
+++ b/src/x87/macro-assembler-x87.h
@@ -22,6 +22,7 @@ const Register kInterpreterAccumulatorRegister = {Register::kCode_eax};
 const Register kInterpreterRegisterFileRegister = {Register::kCode_edx};
 const Register kInterpreterBytecodeOffsetRegister = {Register::kCode_ecx};
 const Register kInterpreterBytecodeArrayRegister = {Register::kCode_edi};
+const Register kJavaScriptCallArgCountRegister = {Register::kCode_eax};
 const Register kRuntimeCallFunctionRegister = {Register::kCode_ebx};
 const Register kRuntimeCallArgCountRegister = {Register::kCode_eax};