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

test/cctest/test-macro-assembler-x64.cc

Index: test/cctest/test-macro-assembler-x64.cc
diff --git a/test/cctest/test-macro-assembler-x64.cc b/test/cctest/test-macro-assembler-x64.cc
index cfdb75d1e869f84f25b8f2270ad074c19fd593f7..1f6c2472885d53167593b11c71298ce8766b93c7 100644
--- a/test/cctest/test-macro-assembler-x64.cc
+++ b/test/cctest/test-macro-assembler-x64.cc
@@ -176,7 +176,7 @@ TEST(SmiMove) {
   EntryCode(masm);
   Label exit;
 
-  TestMoveSmi(masm, &exit, 1, Smi::FromInt(0));
+  TestMoveSmi(masm, &exit, 1, Smi::kZero);
   TestMoveSmi(masm, &exit, 2, Smi::FromInt(127));
   TestMoveSmi(masm, &exit, 3, Smi::FromInt(128));
   TestMoveSmi(masm, &exit, 4, Smi::FromInt(255));
@@ -315,7 +315,7 @@ TEST(Integer32ToSmi) {
   __ movq(rax, Immediate(1));  // Test number.
   __ movl(rcx, Immediate(0));
   __ Integer32ToSmi(rcx, rcx);
-  __ Set(rdx, reinterpret_cast<intptr_t>(Smi::FromInt(0)));
+  __ Set(rdx, reinterpret_cast<intptr_t>(Smi::kZero));
   __ cmpq(rcx, rdx);
   __ j(not_equal, &exit);
 
@@ -352,7 +352,7 @@ TEST(Integer32ToSmi) {
   __ movq(rax, Immediate(6));  // Test number.
   __ movl(rcx, Immediate(0));
   __ Integer32ToSmi(r8, rcx);
-  __ Set(rdx, reinterpret_cast<intptr_t>(Smi::FromInt(0)));
+  __ Set(rdx, reinterpret_cast<intptr_t>(Smi::kZero));
   __ cmpq(r8, rdx);
   __ j(not_equal, &exit);