Perf experiment (to be reverted): use system malloc on Mac.

BUG=310744
R=abarth@chromium.org
TBR=abarth@chromium.org

Review URL: https://codereview.chromium.org/35423009

git-svn-id: http://src.chromium.org/svn/trunk/src/build@230577 4ff67af0-8c30-449e-8e8b-ad334ec8d88c

common.gypi

@@ -1922,6 +1922,7 @@
       # Set this to use the new DX11 version of ANGLE.
       # TODO(apatrick): Remove this when the transition is complete.
       'ANGLE_DX11',
+      'WTF_USE_SYSTEM_MALLOC=1',
     ],
     'conditions': [
       ['(OS=="mac" or OS=="ios") and asan==1', {