MIPS: Followup 'Introduce BUILTIN_CALL_PAIR.'

Port 433e8848

Add DCHECK()s for BUILTIN_CALL, BUILTIN_CALL_PAIR to simulators.

BUG=

Review URL: https://codereview.chromium.org/1630783002

Cr-Commit-Position: refs/heads/master@{#33500}

src/mips/simulator-mips.cc

@@ -2207,6 +2207,8 @@ void Simulator::SoftwareInterrupt(Instruction* instr) {
       *sim_result = result;
       set_register(v0, arg0);
     } else {
+      DCHECK(redirection->type() == ExternalReference::BUILTIN_CALL ||
+             redirection->type() == ExternalReference::BUILTIN_CALL_PAIR);
       SimulatorRuntimeCall target =
                   reinterpret_cast<SimulatorRuntimeCall>(external);
       if (::v8::internal::FLAG_trace_sim) {

src/mips64/simulator-mips64.cc

@@ -2196,6 +2196,8 @@ void Simulator::SoftwareInterrupt(Instruction* instr) {
       *sim_result = result;
       set_register(v0, arg0);
     } else {
+      DCHECK(redirection->type() == ExternalReference::BUILTIN_CALL ||
+             redirection->type() == ExternalReference::BUILTIN_CALL_PAIR);
       SimulatorRuntimeCall target =
                   reinterpret_cast<SimulatorRuntimeCall>(external);
       if (::v8::internal::FLAG_trace_sim) {