S390: Remove more dead code now that legacy const is gone

src/full-codegen/s390/full-codegen-s390.cc

Index: src/full-codegen/s390/full-codegen-s390.cc
diff --git a/src/full-codegen/s390/full-codegen-s390.cc b/src/full-codegen/s390/full-codegen-s390.cc
index efebab2abcd0d54a72e34e3adb73e436db3b7c5a..d84f9f1bd0f518a8350f903396f4c6c5208dac0e 100644
--- a/src/full-codegen/s390/full-codegen-s390.cc
+++ b/src/full-codegen/s390/full-codegen-s390.cc
@@ -743,15 +743,8 @@ void FullCodeGenerator::VisitVariableDeclaration(
       __ mov(r4, Operand(variable->name()));
       // Declaration nodes are always introduced in one of four modes.
       DCHECK(IsDeclaredVariableMode(mode));
-      // Push initial value, if any.
-      // Note: For variables we must not push an initial value (such as
-      // 'undefined') because we may have a (legal) redeclaration and we
-      // must not destroy the current value.
-      if (hole_init) {
-        __ LoadRoot(r2, Heap::kTheHoleValueRootIndex);
-      } else {
-        __ LoadSmiLiteral(r2, Smi::FromInt(0));  // Indicates no initial value.
-      }
+      DCHECK(!hole_init);
+      __ LoadSmiLiteral(r2, Smi::FromInt(0));  // Indicates no initial value.
       __ Push(r4, r2);
       __ Push(Smi::FromInt(variable->DeclarationPropertyAttributes()));
       __ CallRuntime(Runtime::kDeclareLookupSlot);