Add a tolerance factor to the test.

LayoutTests/TestExpectations

Index: LayoutTests/TestExpectations
diff --git a/LayoutTests/TestExpectations b/LayoutTests/TestExpectations
index a6cc1e877fa30ab286da138599e800a1075c4787..16c030c71668c41112a65c87a0215414bc12dfdd 100644
--- a/LayoutTests/TestExpectations
+++ b/LayoutTests/TestExpectations
@@ -791,7 +791,8 @@ crbug.com/311532 [ Win ] fast/dom/Geolocation/timestamp.html [ Pass Failure ]
 crbug.com/311805 [ Mac ] http/tests/w3c/webperf/submission/Google/resource-timing/html/test_resource_reparenting.html [ Failure Pass ]
 crbug.com/311812 [ Mac XP ] http/tests/security/redirect-BLOCKED-to-localURL.html [ Failure Pass ]
 
-crbug.com/311469 [ Mac ] svg/zoom/page/zoom-zoom-coords.xhtml [ Failure Pass ]
+# Commented this out to get a rebaseline; AFAIK, the test is still flaky.
+#crbug.com/311469 [ Mac ] svg/zoom/page/zoom-zoom-coords.xhtml [ Failure Pass ]
 
 crbug.com/312613 fast/canvas/canvas-blending-pattern-over-gradient.html [ Pass Timeout ]
 
@@ -1639,6 +1640,8 @@ crbug.com/446740 virtual/slimmingpaint/fast/canvas/canvas-measure-text-rtl.html
 
 crbug.com/439840 [ Win Linux Debug ] svg/custom/relative-sized-image.xhtml [ Pass ImageOnlyFailure ]
 
+crbug.com/321237 svg/zoom/page/zoom-zoom-coords.xhtml [ NeedsRebaseline ]
+
 crbug.com/418091 [ Mac ] fast/text/aat-morx.html [ Pass Failure ]
 
 crbug.com/446385 [ Linux Mac ] http/tests/xmlhttprequest/xmlhttprequest-json-response-overflow.html [ Pass Timeout ]