Rebaseline: Mark png-partial-load-as-document.html as leaky

TBR=hiroshige@chromium.org
BUG=640886
NOTRY=true

Review-Url: https://codereview.chromium.org/2275213002
Cr-Commit-Position: refs/heads/master@{#414338}

third_party/WebKit/LayoutTests/LeakExpectations

@@ -115,4 +115,7 @@ crbug.com/619060 [ Linux ] imported/wpt/pointerevents/pointerevent_releasepointe
 crbug.com/619060 [ Linux ] imported/wpt/pointerevents/pointerevent_touch-action-pan-x-pan-y_touch-manual.html  [ Leak ]
 crbug.com/619060 [ Linux ] imported/wpt/pointerevents/pointerevent_touch-action-inherit_highest-parent-none_touch-manual.html  [ Leak ]
 crbug.com/619060 [ Linux ] imported/wpt/pointerevents/pointerevent_pointercancel_touch-manual.html  [ Leak ]
-crbug.com/619060 [ Linux ] imported/wpt/pointerevents/pointerevent_pointerleave_after_pointercancel_touch-manual.html  [ Leak ]
\ No newline at end of file
+crbug.com/619060 [ Linux ] imported/wpt/pointerevents/pointerevent_pointerleave_after_pointercancel_touch-manual.html  [ Leak ]
+
+# Leaks that must be fixed asap.
+crbug.com/640886 [ Linux ] http/tests/images/png-partial-load-as-document.html is leaking [ Leak ]