Add support for enabling DCHECKs in release mode

src/hydrogen-instructions.cc

Index: src/hydrogen-instructions.cc
diff --git a/src/hydrogen-instructions.cc b/src/hydrogen-instructions.cc
index 50103662f562034538ae9eaa23be51297b577460..d2aa5f4962ea7769056e569957d4e06141ca1c7d 100644
--- a/src/hydrogen-instructions.cc
+++ b/src/hydrogen-instructions.cc
@@ -200,7 +200,7 @@ void Range::AddConstant(int32_t value) {
   Representation r = Representation::Integer32();
   lower_ = AddWithoutOverflow(r, lower_, value, &may_overflow);
   upper_ = AddWithoutOverflow(r, upper_, value, &may_overflow);
-#ifdef DEBUG
+#if DCHECK_IS_ON
   Verify();
 #endif
 }
@@ -263,7 +263,7 @@ bool Range::AddAndCheckOverflow(const Representation& r, Range* other) {
   lower_ = AddWithoutOverflow(r, lower_, other->lower(), &may_overflow);
   upper_ = AddWithoutOverflow(r, upper_, other->upper(), &may_overflow);
   KeepOrder();
-#ifdef DEBUG
+#if DCHECK_IS_ON
   Verify();
 #endif
   return may_overflow;
@@ -275,7 +275,7 @@ bool Range::SubAndCheckOverflow(const Representation& r, Range* other) {
   lower_ = SubWithoutOverflow(r, lower_, other->upper(), &may_overflow);
   upper_ = SubWithoutOverflow(r, upper_, other->lower(), &may_overflow);
   KeepOrder();
-#ifdef DEBUG
+#if DCHECK_IS_ON
   Verify();
 #endif
   return may_overflow;
@@ -291,7 +291,7 @@ void Range::KeepOrder() {
 }
 
 
-#ifdef DEBUG
+#if DCHECK_IS_ON
 void Range::Verify() const {
   DCHECK(lower_ <= upper_);
 }
@@ -306,7 +306,7 @@ bool Range::MulAndCheckOverflow(const Representation& r, Range* other) {
   int v4 = MulWithoutOverflow(r, upper_, other->upper(), &may_overflow);
   lower_ = Min(Min(v1, v2), Min(v3, v4));
   upper_ = Max(Max(v1, v2), Max(v3, v4));
-#ifdef DEBUG
+#if DCHECK_IS_ON
   Verify();
 #endif
   return may_overflow;
@@ -735,7 +735,7 @@ bool HInstruction::Dominates(HInstruction* other) {
 }
 
 
-#ifdef DEBUG
+#if DCHECK_IS_ON
 void HInstruction::Verify() {
   // Verify that input operands are defined before use.
   HBasicBlock* cur_block = block();
@@ -4549,8 +4549,8 @@ bool HValue::HasNonSmiUse() {
 }
 
 
-// Node-specific verification code is only included in debug mode.
-#ifdef DEBUG
+// Node-specific verification code is only included when DCHECKs are enabled.
+#if DCHECK_IS_ON
 
 void HPhi::Verify() {
   DCHECK(OperandCount() == block()->predecessors()->length());