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

src/ppc/macro-assembler-ppc.h

Index: src/ppc/macro-assembler-ppc.h
diff --git a/src/ppc/macro-assembler-ppc.h b/src/ppc/macro-assembler-ppc.h
index f4f7d5cc1a5468a2c6dd64067948ad3db7b059e9..def6894dfbf71afef829527bfaa5ca3cde9f976c 100644
--- a/src/ppc/macro-assembler-ppc.h
+++ b/src/ppc/macro-assembler-ppc.h
@@ -23,6 +23,7 @@ const Register kInterpreterRegisterFileRegister = {Register::kCode_r14};
 const Register kInterpreterBytecodeOffsetRegister = {Register::kCode_r15};
 const Register kInterpreterBytecodeArrayRegister = {Register::kCode_r16};
 const Register kInterpreterDispatchTableRegister = {Register::kCode_r17};
+const Register kJavaScriptCallArgCountRegister = {Register::kCode_r3};
 const Register kRuntimeCallFunctionRegister = {Register::kCode_r4};
 const Register kRuntimeCallArgCountRegister = {Register::kCode_r3};