Add Crankshaft support for smi-only elements

src/arm/lithium-codegen-arm.cc

Index: src/arm/lithium-codegen-arm.cc
diff --git a/src/arm/lithium-codegen-arm.cc b/src/arm/lithium-codegen-arm.cc
index 1e98f6704ba4a16fc57100cc53690352a5d98985..f89cf76334f6819a6b3377f2ad40f70e761e3af2 100644
--- a/src/arm/lithium-codegen-arm.cc
+++ b/src/arm/lithium-codegen-arm.cc
@@ -3342,6 +3342,13 @@ void LCodeGen::DoStoreKeyedFastElement(LStoreKeyedFastElement* instr) {
   Register key = instr->key()->IsRegister() ? ToRegister(instr->key()) : no_reg;
   Register scratch = scratch0();
 
+  // This instruction cannot handle the FAST_SMI_ONLY_ELEMENTS -> FAST_ELEMENTS
+  // conversion, so it deopts in that case.
+  if (instr->hydrogen()->ValueNeedsSmiCheck()) {
+    __ tst(value, Operand(kSmiTagMask));
+    DeoptimizeIf(ne, instr->environment());
+  }
+
   // Do the store.
   if (instr->key()->IsConstantOperand()) {
     ASSERT(!instr->hydrogen()->NeedsWriteBarrier());