[compiler] Make --debug-code the default in debug builds.

test/mjsunit/regress/regress-353551.js

 // Copyright 2014 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 12 matching lines @@
 // DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
 // THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 // (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 // OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 
 var depth = 0;
 function __f_3(x) {
   var __v_1 = arguments;
   __v_1[1000] = 123;
   depth++;
-  if (depth > 2400) return;
+  if (depth > 2200) return;
   function __f_4() {
     ++__v_1[0];
     __f_3(0.5);
   };
   __f_4();
 }
 __f_3(0.5);