[crankshaft] Fix Smi overflow in {HMaybeGrowElements}.

src/crankshaft/mips64/lithium-codegen-mips64.cc

 // Copyright 2012 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "src/crankshaft/mips64/lithium-codegen-mips64.h"
 
 #include "src/builtins/builtins-constructor.h"
 #include "src/code-factory.h"
 #include "src/code-stubs.h"
 #include "src/crankshaft/hydrogen-osr.h"
@@ skipping 4231 matching lines @@
   {
     PushSafepointRegistersScope scope(this);
     if (instr->object()->IsRegister()) {
       __ mov(result, ToRegister(instr->object()));
     } else {
       __ ld(result, ToMemOperand(instr->object()));
     }
 
     LOperand* key = instr->key();
     if (key->IsConstantOperand()) {
-      LConstantOperand* constant_key = LConstantOperand::cast(key);
-      int32_t int_key = ToInteger32(constant_key);
-      if (Smi::IsValid(int_key)) {
-        __ li(a3, Operand(Smi::FromInt(int_key)));
-      } else {
-        // We should never get here at runtime because there is a smi check on
-        // the key before this point.
-        __ stop("expected smi");
-      }
+      __ li(a3, Operand(ToSmi(LConstantOperand::cast(key))));
     } else {
       __ mov(a3, ToRegister(key));
       __ SmiTag(a3);
     }
 
     GrowArrayElementsStub stub(isolate(), instr->hydrogen()->kind());
     __ mov(a0, result);
     __ CallStub(&stub);
     RecordSafepointWithLazyDeopt(
         instr, RECORD_SAFEPOINT_WITH_REGISTERS_AND_NO_ARGUMENTS);
@@ skipping 1367 matching lines @@
   __ ld(result, FieldMemOperand(scratch,
                                 FixedArray::kHeaderSize - kPointerSize));
   __ bind(deferred->exit());
   __ bind(&done);
 }
 
 #undef __
 
 }  // namespace internal
 }  // namespace v8