Sign extend the dehoisted key at the definition point for x64 port only; for x32 port, we need to si

src/x64/lithium-x64.cc

Index: src/x64/lithium-x64.cc
diff --git a/src/x64/lithium-x64.cc b/src/x64/lithium-x64.cc
index bb2ecc06b8e4e374e838cf2847f08221ed9f8faa..b8c5b9905c99feb9becf0ce3c7344ef249f47598 100644
--- a/src/x64/lithium-x64.cc
+++ b/src/x64/lithium-x64.cc
@@ -2110,6 +2110,7 @@ LInstruction* LChunkBuilder::DoLoadRoot(HLoadRoot* instr) {
 
 
 void LChunkBuilder::FindDehoistedKeyDefinitions(HValue* candidate) {
+  ASSERT(kPointerSize == kInt64Size);
   BitVector* dehoisted_key_ids = chunk_->GetDehoistedKeyIds();
   if (dehoisted_key_ids->Contains(candidate->id())) return;
   dehoisted_key_ids->Add(candidate->id());
@@ -2126,7 +2127,7 @@ LInstruction* LChunkBuilder::DoLoadKeyed(HLoadKeyed* instr) {
   LOperand* key = UseRegisterOrConstantAtStart(instr->key());
   LInstruction* result = NULL;
 
-  if (instr->IsDehoisted()) {
+  if ((kPointerSize == kInt64Size) && instr->IsDehoisted()) {
     FindDehoistedKeyDefinitions(instr->key());
   }
 
@@ -2171,7 +2172,7 @@ LInstruction* LChunkBuilder::DoLoadKeyedGeneric(HLoadKeyedGeneric* instr) {
 LInstruction* LChunkBuilder::DoStoreKeyed(HStoreKeyed* instr) {
   ElementsKind elements_kind = instr->elements_kind();
 
-  if (instr->IsDehoisted()) {
+  if ((kPointerSize == kInt64Size) && instr->IsDehoisted()) {
     FindDehoistedKeyDefinitions(instr->key());
   }