I've tried both GYP and GN, and all kinds of flags, the tests always timeout randomly for me. It's a different set of tests each time, and if I run any of the tests individually everything works fine.

ninja: Entering directory `out/Release'
ninja: no work to do.
Using port 'linux-trusty'
Test configuration: <trusty, x86_64, release>
View the test results at file:///media/Checkouts/blink/src/out/Release/layout-test-results/results.html
View the archived results dashboard at file:///media/Checkouts/blink/src/out/Release/layout-test-results/dashboard.html
Baseline search path: linux -> win -> generic
Using Release build
Pixel tests enabled
Regular timeout: 6000, slow test timeout: 30000
Command line: /media/Checkouts/blink/src/out/Release/content_shell --run-layout-test --enable-crash-reporter --crash-dumps-dir=/media/Checkouts/blink/src/out/Release/crash-dumps -

Found 1925 tests; running 1922, skipping 3.
                  
Running 32 content_shells in parallel.                                      

[1/1922] fast/dom/HTMLAreaElement/area-cursor.html failed unexpectedly (test timed out)
[2/1922] fast/dom/DeviceLight/add-listener.html failed unexpectedly (test timed out)
[3/1922] fast/dom/CompositorPr...oxy-forces-layer.html failed unexpectedly (test timed out)
[4/1922] fast/dom/CSSStyleDecl...est-css-property.html failed unexpectedly (test timed out)
[5/1922] fast/dom/DOMImplement...ment-XMLDocument.html failed unexpectedly (test timed out)
[6/1922] fast/dom/DeviceOrient...er-from-callback.html failed unexpectedly (test timed out)
[7/1922] fast/dom/HTMLCollecti...alidate-no-crash.html failed unexpectedly (test timed out)
[8/1922] fast/dom/HTMLHeadElement/head-check.html failed unexpectedly (test timed out)
[9/1922] fast/dom/Element/attr-param-typechecking.html failed unexpectedly (test timed out)
[10/1922] fast/dom/HTMLBodyEle...ing-iframe-crash.html failed unexpectedly (test timed out)
[11/1922] fast/dom/Comment/comment-constructor.html failed unexpectedly (test timed out)
[12/1922] fast/dom/HTMLElement...before-text-node.html failed unexpectedly (test timed out)
[13/1922] fast/dom/DocumentFra...ment-constructor.html failed unexpectedly (test timed out)
[14/1922] fast/dom/DocumentType/clone-node.html failed unexpectedly (test timed out)
[15/1922] fast/dom/Attr/access...ment-destruction.html failed unexpectedly (test timed out)
[16/1922] fast/dom/Document/ad...ode-with-doctype.html failed unexpectedly (test timed out)
[17/1922] fast/dom/Document/Ca...eFromPoint/basic.html failed unexpectedly (test timed out)
[18/1922] fast/dom/34176.html failed unexpectedly (test timed out)
[19/1922] fast/dom/HTMLHrEleme...oshade-attribute.html failed unexpectedly (test timed out)
[20/1922] fast/dom/HTMLHtmlEle...ml-element-crash.html failed unexpectedly (test timed out)
[21/1922] fast/dom/DeviceMotio...-during-dispatch.html failed unexpectedly (test timed out)
[22/1922] fast/dom/HTMLFormEle.../adopt-assertion.html failed unexpectedly (test timed out)
[23/1922] fast/dom/HTMLFontElement/size-attribute.html failed unexpectedly (test timed out)
[24/1922] fast/dom/HTMLDocumen...e-element-frames.html failed unexpectedly (test timed out)
[25/1922] fast/dom/HTMLDivElement/align/getset.html failed unexpectedly (test timed out)
[26/1922] fast/dom/HTMLButtonElement/change-type.html failed unexpectedly (test timed out)
[27/1922] fast/dom/DOMException/XPathException.html failed unexpectedly (test timed out)
[28/1922] fast/dom/HTMLDialogE...os-dialog-layout.html failed unexpectedly (test timed out)
[29/1922] fast/dom/Geolocation/argument-types.html failed unexpectedly (test timed out)
[30/1922] fast/dom/HTMLBaseEle...pect-to-document.html failed unexpectedly (test timed out)
[31/1922] fast/dom/HTMLButtonElement/value/getset.html failed unexpectedly (test timed out)
[32/1922] fast/dom/HTMLAnchorE...r-download-unset.html failed unexpectedly (test timed out)