add ignore_edge option in test list.

tests/selenium/javascript_unit_test_list.txt

 #
 # Test Requirements:
 #
 #   Each sample is expected to have a global variable called g_testResult
 #   That starts undefined and is set to true or false when the test is finished.
 #
 # Line Format:
 #
 #   TestType test-name options
 #
@@ skipping 31 matching lines @@
 #   pdiff_threshold(number_of_pixels_allowed) : Number of pixels
 #       allowed to be perceptually different before the test fails.
 #       "pdiff_threshold" specifies the threshold for all
 #       platforms.  Platform specific versions override the
 #       threshold for that platform.  The default threshold is 10 pixels.
 #
 #   except(*firefox, *iexplore, *googlechrome) : Name of the browser
 #       environment(s) where the test should be skipped.
 #       Default = ""
 #
+#   pdiff_edge_ignore_off : Turn off edge detection function in pdiff. 
+#       By default, it's on with a default edge detect threshold 5.
+#
+#   pdiff_edge_threshold(0 to 7) : Set edge detect threshold in pdiff.
+#       This threshold indicates the max number of neighbors the pixel can
+#       have to be considered as edge. 0 means only ignore scattered pixels.
 # NOTE! ----------------------------------------------------------------------
 #
 # Read the sample guidelines
 # http://wiki.corp.google.com/twiki/bin/view/Main/ClientThreeDSampleGuidelines
 #
 #
 small   version-check-test
 small   event-test
 small   test-test
 small   serialization-test
 small   math-test
 small   features-test         except(*iexplore)
 small   quaternion-test
 # TODO Temporarily removing until V8 bug is fixed
 small   v8-test
 small   init-status-test
 small   quaternion-test
 small   base-test
 small   util-test
-small   pixel-perfection      screenshot pdiff_threshold(2500) pdiff_threshold_mac(3000) except(*iexplore)
+small   pixel-perfection      screenshot pdiff_threshold(200) pdiff_threshold_mac(3000) except(*iexplore)
 medium  offscreen-test
 medium  texture-set-test      screenshot
 medium  param-array-test      screenshot
 small   no-rendergraph        screenshot
-small   non-cachable-params   screenshot pdiff_threshold(1700)
+small   non-cachable-params   screenshot pdiff_threshold(200)
 small   type-test
 small   render-test
 # TODO Test disabled, as the behaviour on Chrome does not match other
 #  browsers - objects are not deleted properly.
 small   ownership-test
 small   effect-import-test
 
 # -- tests below this line are tests for which there is a python
 #    function to custom run the test. As such, only the 'except' and
 #    pdiff_threshold options have any meaning
 
 # These two tests rely on Selenium getting or setting a page's title and that
 # does not currently work with Chrome.
 medium  TestStressDrawShapes   except(*googlechrome)
 medium  TestStressMultiWindow  except(*googlechrome)
 
-large   TestStressCullingZSort pdiff_threshold(14100)
+large   TestStressCullingZSort pdiff_threshold(200)