Mark certain layout tests slow on MSAN bots.

third_party/WebKit/LayoutTests/MSANExpectations

Index: third_party/WebKit/LayoutTests/MSANExpectations
diff --git a/third_party/WebKit/LayoutTests/MSANExpectations b/third_party/WebKit/LayoutTests/MSANExpectations
index 2c2d9107cd1db35c6695fa8aa5c067b46bea542d..b85495d2f8347eca66dd41489b89335e1aa28c1b 100644
--- a/third_party/WebKit/LayoutTests/MSANExpectations
+++ b/third_party/WebKit/LayoutTests/MSANExpectations
@@ -52,3 +52,12 @@ crbug.com/577889 [ Linux ] fast/js/typed-array-allocation-failure.html [ Crash ]
 
 # These tests use OpenGl, which crashes on MSAN builds due to missing instrumentation
 crbug.com/555703 [ Linux ] virtual/media-gpu-accelerated [ Skip ]
+
+# These tests are just a tad bit too slow on MSAN bots, give them more time.
+crbug.com/729136 [ Linux ] external/wpt/encoding/textdecoder-fatal-single-byte.html [ Slow ]
+crbug.com/729136 [ Linux ] fast/css/css-selector-deeply-nested.html [ Slow ]
+crbug.com/729136 [ Linux ] http/tests/inspector/forced-layout-in-microtask.html [ Slow ]
+crbug.com/729136 [ Linux ] http/tests/inspector/tracing/timeline-xhr-response-type-blob-event.html [ Slow ]
+crbug.com/729136 [ Linux ] inspector/components/file-path-scoring.html [ Slow ]
+crbug.com/729136 [ Linux ] inspector/elements/styles-4/styles-should-not-force-sync-style-recalc.html [ Slow ]
+crbug.com/729136 [ Linux ] webaudio/mixing.html [ Slow ]