[stubs] Drop CallApiCallbackStub::call_data_undefined optimization.

src/mips/code-stubs-mips.cc

Index: src/mips/code-stubs-mips.cc
diff --git a/src/mips/code-stubs-mips.cc b/src/mips/code-stubs-mips.cc
index 82b76baf80ae427508867b40e127843f14cf1e87..0fcdafca21d8321b86f5dd248382c71c63b31fa4 100644
--- a/src/mips/code-stubs-mips.cc
+++ b/src/mips/code-stubs-mips.cc
@@ -2973,9 +2973,7 @@ void CallApiCallbackStub::Generate(MacroAssembler* masm) {
   }
 
   Register scratch = call_data;
-  if (!call_data_undefined()) {
-    __ LoadRoot(scratch, Heap::kUndefinedValueRootIndex);
-  }
+  __ LoadRoot(scratch, Heap::kUndefinedValueRootIndex);
   // Push return value and default return value.
   __ Push(scratch, scratch);
   __ li(scratch, Operand(ExternalReference::isolate_address(masm->isolate())));