Add support for enabling DCHECKs in release mode

src/frames.cc

Index: src/frames.cc
diff --git a/src/frames.cc b/src/frames.cc
index 0ba8ea0020ed379dc2d70fe423b6ac00d983f6f1..7c3a6741760ba2fb22eec0bc864d219bbb597c13 100644
--- a/src/frames.cc
+++ b/src/frames.cc
@@ -386,7 +386,7 @@ bool StackFrame::HasHandler() const {
 }
 
 
-#ifdef DEBUG
+#if DCHECK_IS_ON
 static bool GcSafeCodeContains(HeapObject* object, Address addr);
 #endif
 
@@ -440,7 +440,7 @@ StackFrame::Type StackFrame::ComputeType(const StackFrameIteratorBase* iterator,
 }
 
 
-#ifdef DEBUG
+#if DCHECK_IS_ON
 bool StackFrame::can_access_heap_objects() const {
   return iterator_->can_access_heap_objects_;
 }
@@ -1450,7 +1450,7 @@ static int GcSafeSizeOfCodeSpaceObject(HeapObject* object) {
 }
 
 
-#ifdef DEBUG
+#if DCHECK_IS_ON
 static bool GcSafeCodeContains(HeapObject* code, Address addr) {
   Map* map = GcSafeMapOfCodeSpaceObject(code);
   DCHECK(map == code->GetHeap()->code_map());