Assume users are using Xcode 5.1.

common.gypi

@@ -113,9 +113,9 @@
         'conditions': [
           ['OS=="mac"', {
             'xcode_settings': {
-              'GCC_TREAT_WARNINGS_AS_ERRORS': 'NO',
               'WARNING_CFLAGS': [
                 '-Wno-deprecated-declarations',
+                '-Wno-deprecated-register',
                 '-Wno-unused-private-field',
                 '-Wno-unused-function',
               ],

docs/development/build-instructions-mac.md

@@ -3,7 +3,7 @@
 ## Prerequisites
 
 * Mac OS X >= 10.7
-* [Xcode](https://developer.apple.com/technologies/tools/)
+* [Xcode](https://developer.apple.com/technologies/tools/) >= 5.1
 * [node.js](http://nodejs.org)
 
 If you are using the python downloaded by Homebrew, you also need to install