Add Smi::Zero and replace all Smi::FromInt(0) calls

test/unittests/interpreter/bytecode-array-iterator-unittest.cc

Index: test/unittests/interpreter/bytecode-array-iterator-unittest.cc
diff --git a/test/unittests/interpreter/bytecode-array-iterator-unittest.cc b/test/unittests/interpreter/bytecode-array-iterator-unittest.cc
index 07ecefb5293e18dd8dff7cbb1f9d09e69f36c0ad..ff5e7e5c212d30ad21a62767fe5e366bc56ea8cf 100644
--- a/test/unittests/interpreter/bytecode-array-iterator-unittest.cc
+++ b/test/unittests/interpreter/bytecode-array-iterator-unittest.cc
@@ -26,7 +26,7 @@ TEST_F(BytecodeArrayIteratorTest, IteratesBytecodeArray) {
   Factory* factory = isolate()->factory();
   Handle<HeapObject> heap_num_0 = factory->NewHeapNumber(2.718);
   Handle<HeapObject> heap_num_1 = factory->NewHeapNumber(2147483647);
-  Smi* zero = Smi::FromInt(0);
+  Smi* zero = Smi::kZero;
   Smi* smi_0 = Smi::FromInt(64);
   Smi* smi_1 = Smi::FromInt(-65536);
   Register reg_0(0);