Fix broken test on chromebook

  - test skip chromebook where it should not.

BUG=chromium:521356
TEST=None

Change-Id: I3d106467f5af63964fec2c3cfcfefaa99c4ad328
Previous-Reviewed-on: https://chromium-review.googlesource.com/296125
(cherry picked from commit 576b98a67baf78bddc0bf6125c46ec6d3fb36308)
Reviewed-on: https://chromium-review.googlesource.com/304321
Reviewed-by: danny chan <dchan@chromium.org>
Commit-Queue: danny chan <dchan@chromium.org>
Tested-by: danny chan <dchan@chromium.org>
Reviewed-by: Rohit Makasana <rohitbm@chromium.org>
diff --git a/server/site_tests/platform_PowerStatusStress/platform_PowerStatusStress.py b/server/site_tests/platform_PowerStatusStress/platform_PowerStatusStress.py
index ebf007f..7302c1d 100644
--- a/server/site_tests/platform_PowerStatusStress/platform_PowerStatusStress.py
+++ b/server/site_tests/platform_PowerStatusStress/platform_PowerStatusStress.py
@@ -118,7 +118,7 @@
     def run_once(self, host, loop_count):
         self.host = host
         dut_type = host.get_board_type()
-        if dut_type is not 'CHROMEBOOK':
+        if dut_type != 'CHROMEBOOK':
             raise error.TestError(
                     'This test is not supported on %s' %  dut_type)
         self.autotest_client = autotest.Autotest(self.host)