Add SLOW expectation for virtual/spv2/fast/overflow/lots-of-sibling-inline-boxes.html

BUG=594189
NOTRY=true

Review URL: https://codereview.chromium.org/1786763002

Cr-Commit-Position: refs/heads/master@{#380697}
diff --git a/third_party/WebKit/LayoutTests/SlowTests b/third_party/WebKit/LayoutTests/SlowTests
index 3fcee72..a9113f27 100644
--- a/third_party/WebKit/LayoutTests/SlowTests
+++ b/third_party/WebKit/LayoutTests/SlowTests
@@ -284,3 +284,5 @@
 crbug.com/584807 virtual/threaded/printing/webgl-oversized-printing.html [ Slow ]
 
 crbug.com/592183 usb/usbDevice.html [ Slow ]
+
+crbug.com/594189 virtual/spv2/fast/overflow/lots-of-sibling-inline-boxes.html [ Slow ]