Switch Isolate to noop on Mac

build/common.gypi

Index: build/common.gypi
diff --git a/build/common.gypi b/build/common.gypi
index d39128b1e23488a54a4aa840dd5caf5af1b20df6..3d384df3608f7041d741858f422ad26c82733237 100644
--- a/build/common.gypi
+++ b/build/common.gypi
@@ -631,10 +631,12 @@
         # overriden with GYP_DEFINES.
         # TODO(maruel): Remove the conditions as more configurations are
         # supported.
+        # TODO(csharp): Remove OS!="mac" once xcode can run the isolate code
+        # again.
         # NOTE: The check for disable_nacl==0 and component=="static_library"
         # can't be used here because these variables are not defined yet, but it
         # is still not supported.
-        ['inside_chromium_build==1 and OS!="ios" and OS!="android" and chromeos==0', {
+        ['inside_chromium_build==1 and OS!="mac" and OS!="ios" and OS!="android" and chromeos==0', {
           'test_isolation_mode%': 'check',
         }, {
           'test_isolation_mode%': 'noop',