Bug 1392640 - Only use preference based whitelisting for Linux. r=haik

MozReview-Commit-ID: IWNnRcLMreI

--HG--
extra : rebase_source : 9802f3e8c251aab58ef6f181d6066b5e020909a3

layout/tools/reftest/runreftest.py

@@ -310,11 +310,12 @@ class RefTest(object):
                 sandbox_whitelist_paths.append(options.workPath)
         except AttributeError:
             pass
-        try:
-            if options.objPath:
-                sandbox_whitelist_paths.append(options.objPath)
-        except AttributeError:
-            pass
+        if platform.system() == "Linux":
+            try:
+                if options.objPath:
+                    sandbox_whitelist_paths.append(options.objPath)
+            except AttributeError:
+                pass
         if (platform.system() == "Linux" or
             platform.system() in ("Windows", "Microsoft")):
             # Trailing slashes are needed to indicate directories on Linux and Windows