Don't add code dependencies eagerly for HCheckMaps.

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 e8dd5bb63f02b7f79ff3ff9ca9438260fe9ee079..eb9e7dd00a6a79d97563d219db5a70d7afbeb7d8 100644
--- a/src/x64/lithium-x64.cc
+++ b/src/x64/lithium-x64.cc
@@ -1935,15 +1935,12 @@ LInstruction* LChunkBuilder::DoCheckValue(HCheckValue* instr) {
 
 
 LInstruction* LChunkBuilder::DoCheckMaps(HCheckMaps* instr) {
-  LOperand* value = NULL;
-  if (!instr->CanOmitMapChecks()) {
-    value = UseRegisterAtStart(instr->value());
-    if (instr->has_migration_target()) info()->MarkAsDeferredCalling();
-  }
-  LInstruction* result = new(zone()) LCheckMaps(value);
-  if (!instr->CanOmitMapChecks()) {
-    result = AssignEnvironment(result);
-    if (instr->has_migration_target()) result = AssignPointerMap(result);
+  if (instr->IsStabilityCheck()) return new(zone()) LCheckMaps;
+  LOperand* value = UseRegisterAtStart(instr->value());
+  LInstruction* result = AssignEnvironment(new(zone()) LCheckMaps(value));
+  if (instr->HasMigrationTarget()) {
+    info()->MarkAsDeferredCalling();
+    result = AssignPointerMap(result);
   }
   return result;
 }