Mark vr/getFrameData_samewithinframe.html as flaky

TBR=rogerta
NOTRY=true

Bug: 745899
Change-Id: I04c8e24149b278a16e2cf14762ca965c91b8cec3
Reviewed-on: https://chromium-review.googlesource.com/576381
Commit-Queue: Alexei Filippov <alph@chromium.org>
Reviewed-by: Alexei Filippov <alph@chromium.org>
Cr-Commit-Position: refs/heads/master@{#487562}

third_party/WebKit/LayoutTests/TestExpectations

@@ -3103,3 +3103,4 @@ crbug.com/708994 virtual/mojo-loading/http/tests/security/cross-frame-mouse-sour
 crbug.com/626703 [ Win7 ] external/wpt/html/semantics/tabular-data/processing-model-1/span-limits.html [ Timeout ]
 
 crbug.com/745887 [ Mac Win ] fast/frames/sandboxed-iframe-plugins.html [ Failure Pass ]
+crbug.com/745899 [ Linux ] vr/getFrameData_samewithinframe.html [ Failure Pass ]