Mark some flexbox tests as leaky on Linux

third_party/WebKit/LayoutTests/LeakExpectations

Index: third_party/WebKit/LayoutTests/LeakExpectations
diff --git a/third_party/WebKit/LayoutTests/LeakExpectations b/third_party/WebKit/LayoutTests/LeakExpectations
index 1ba76dff8a106e88c248980c59e7a47aaed27a76..25c56170fbdfebe7173962fa8df6357dcb4d817a 100644
--- a/third_party/WebKit/LayoutTests/LeakExpectations
+++ b/third_party/WebKit/LayoutTests/LeakExpectations
@@ -139,3 +139,12 @@ crbug.com/451577 [ Linux ] inspector/extensions/extensions-sidebar.html [ Slow ]
 crbug.com/578297 [ Linux ] media/video-autoplay-experiment-modes.html [ Slow ]
 crbug.com/578297 [ Linux ] virtual/threaded/printing/webgl-oversized-printing.html [ Slow ]
 crbug.com/578297 [ Linux ] http/tests/media/media-source/mediasource-appendstream-quota-exceeded.html [ Slow ]
+
+# -----------------------------------------------------------------
+# Leaks in imported/csswg-test/vendor-imports/mozilla/mozilla-central-reftests/flexbox/*
+# -----------------------------------------------------------------
+crbug.com/594603 [ Linux ] imported/csswg-test/vendor-imports/mozilla/mozilla-central-reftests/flexbox/flexbox-baseline-align-self-baseline-vert-001.html [ Leak ]
+crbug.com/594603 [ Linux ] imported/csswg-test/vendor-imports/mozilla/mozilla-central-reftests/flexbox/flexbox-baseline-empty-001a.html [ Leak ]
+crbug.com/594603 [ Linux ] imported/csswg-test/vendor-imports/mozilla/mozilla-central-reftests/flexbox/flexbox-baseline-empty-001b.html [ Leak ]
+crbug.com/594603 [ Linux ] imported/csswg-test/vendor-imports/mozilla/mozilla-central-reftests/flexbox/flexbox-baseline-multi-item-vert-001.html [ Leak ]
+crbug.com/594603 [ Linux ] imported/csswg-test/vendor-imports/mozilla/mozilla-central-reftests/flexbox/flexbox-whitespace-handling-002.xhtml [ Leak ]