[turbofan] Make new.target explicit in JSCallDescriptor.

src/mips64/macro-assembler-mips64.h

Index: src/mips64/macro-assembler-mips64.h
diff --git a/src/mips64/macro-assembler-mips64.h b/src/mips64/macro-assembler-mips64.h
index 0e88ca4d6d68f91cc5f38f9f0d484eb05a8c0436..f4c28546e87a4f06663da549a1f8e4ea3043fc43 100644
--- a/src/mips64/macro-assembler-mips64.h
+++ b/src/mips64/macro-assembler-mips64.h
@@ -23,6 +23,7 @@ const Register kInterpreterBytecodeOffsetRegister = {Register::kCode_t0};
 const Register kInterpreterBytecodeArrayRegister = {Register::kCode_t1};
 const Register kInterpreterDispatchTableRegister = {Register::kCode_t2};
 const Register kJavaScriptCallArgCountRegister = {Register::kCode_a0};
+const Register kJavaScriptCallNewTargetRegister = {Register::kCode_a3};
 const Register kRuntimeCallFunctionRegister = {Register::kCode_a1};
 const Register kRuntimeCallArgCountRegister = {Register::kCode_a0};