[turbofan] Use CompareNilIC for abstract equality with null/undefined.

src/full-codegen/mips/full-codegen-mips.cc

Index: src/full-codegen/mips/full-codegen-mips.cc
diff --git a/src/full-codegen/mips/full-codegen-mips.cc b/src/full-codegen/mips/full-codegen-mips.cc
index 13484a87b44a53bca48f23169a4f8de8f459df3d..a0164937d771e733112d7fb42a0ab039ca5e40e1 100644
--- a/src/full-codegen/mips/full-codegen-mips.cc
+++ b/src/full-codegen/mips/full-codegen-mips.cc
@@ -4957,7 +4957,8 @@ void FullCodeGenerator::EmitLiteralCompareNil(CompareOperation* expr,
   } else {
     Handle<Code> ic = CompareNilICStub::GetUninitialized(isolate(), nil);
     CallIC(ic, expr->CompareOperationFeedbackId());
-    Split(ne, v0, Operand(zero_reg), if_true, if_false, fall_through);
+    __ LoadRoot(a1, Heap::kTrueValueRootIndex);
+    Split(eq, v0, Operand(a1), if_true, if_false, fall_through);
   }
   context()->Plug(if_true, if_false);
 }