Mark http/tests/appcache/non-html.xhtml as flakily leaking.

BUG=835943
NOTRY=true

Change-Id: I468b0d573bf5cda24e930e34ea7ae7a581202713
Reviewed-on: https://chromium-review.googlesource.com/1024758Reviewed-by: Xida Chen <xidachen@chromium.org>
Commit-Queue: Xida Chen <xidachen@chromium.org>
Cr-Commit-Position: refs/heads/master@{#552797}

third_party/WebKit/LayoutTests/LeakExpectations

@@ -46,6 +46,7 @@ crbug.com/651742 external/wpt/content-security-policy/connect-src/connect-src-be
 crbug.com/780386 external/wpt/html/dom/reflection-grouping.html [ Leak Pass ]
 crbug.com/796944 [ Linux ] synthetic_gestures/synthetic-pinch-zoom-gesture.html [ Leak Pass ]
 crbug.com/667560 [ Linux ] http/tests/devtools/console/console-search.js [ Leak Pass ]
+crbug.com/835943 [ Linux ] http/tests/appcache/non-html.xhtml [ Leak Pass ]
 
 # -----------------------------------------------------------------
 # Not revert suspected CL as jam@ request, expected to be fixed soon.