ART: Implement HSelect with CSEL/FCSEL on arm64

Change-Id: I549af0cba3c5048066a2d1206b78a70b496d349e
diff --git a/compiler/optimizing/nodes.h b/compiler/optimizing/nodes.h
index 2697af3..323cfae 100644
--- a/compiler/optimizing/nodes.h
+++ b/compiler/optimizing/nodes.h
@@ -5997,9 +5997,14 @@
 };
 
 inline int64_t Int64FromConstant(HConstant* constant) {
-  DCHECK(constant->IsIntConstant() || constant->IsLongConstant());
-  return constant->IsIntConstant() ? constant->AsIntConstant()->GetValue()
-                                   : constant->AsLongConstant()->GetValue();
+  if (constant->IsIntConstant()) {
+    return constant->AsIntConstant()->GetValue();
+  } else if (constant->IsLongConstant()) {
+    return constant->AsLongConstant()->GetValue();
+  } else {
+    DCHECK(constant->IsNullConstant());
+    return 0;
+  }
 }
 
 inline bool IsSameDexFile(const DexFile& lhs, const DexFile& rhs) {