The following layout test is both crashing and failing flakily on Win, Linux, Mac:
fast/forms/relayout-shifts-inner-editor.html

See:
https://test-results.appspot.com/dashboards/flakiness_dashboard.html#tests=fast%2Fforms%2Frelayout-shifts-inner-editor.html&showFlaky=true

Often the failures are masked by automatic retries, e.g. in [1] it crashed 3 times before passing (slowing down the tests), but sometimes this causes builds to go red, e.g. [2].

[1]: https://build.chromium.org/p/chromium.webkit/builders/WebKit%20Win7%20(dbg)/builds/7795/steps/webkit_tests/logs/stdio
[2]: https://build.chromium.org/p/chromium.webkit/builders/WebKit%20Linux%20Precise%20(dbg)/builds/698

Example stack trace:

crash log for renderer (pid <unknown>):
STDOUT: layer at (0,0) size 800x600
STDOUT:   LayoutView at (0,0) size 800x600
STDOUT: layer at (0,0) size 800x56
STDOUT:   LayoutBlockFlow {HTML} at (0,0) size 800x56
STDOUT:     LayoutBlockFlow {BODY} at (8,8) size 784x40
STDOUT:       LayoutBlockFlow {DIV} at (0,0) size 784x20
STDOUT:         LayoutText {#text} at (0,0) size 579x19
STDOUT:           text run at (0,0) width 579: "This change checks that the caret in the >input< below doesn't shift out of it after several layouts."
STDOUT:       LayoutBlockFlow {DIV} at (0,20) size 784x20
STDOUT:         LayoutText {#text} at (0,0) size 260x19
STDOUT:           text run at (0,0) width 260: "This test has passed if the caret is centered "
STDOUT:         LayoutInline {B} at (0,0) size 39x19
STDOUT:           LayoutText {#text} at (260,0) size 39x19
STDOUT:             text run at (260,0) width 39: "inside"
STDOUT:         LayoutText {#text} at (299,0) size 73x19
STDOUT:           text run at (299,0) width 73: " the >input<"
STDOUT: layer at (40,0) size 204x56
STDOUT:   LayoutTextControl (positioned) {INPUT} at (40,0) size 204x56 [bgcolor=#FFFFFF] [border: (2px inset #EEEEEE)]
STDOUT: layer at (42,20) size 200x16
STDOUT:   LayoutBlockFlow {DIV} at (2,20) size 200x16
STDOUT: caret: position 0 of child 0 {DIV} of {#document-fragment} of child 4 {INPUT} of body
STDERR: [4:4:1020/064050:3519150464:FATAL:render_widget_compositor.cc(901)] Check failed: !layout_and_paint_async_callback_. 
STDERR: #0 0x7f1b985cda5e base::debug::StackTrace::StackTrace()
STDERR: #1 0x7f1b9863cd8f logging::LogMessage::~LogMessage()
STDERR: #2 0x7f1b9af9d4b0 content::RenderWidgetCompositor::compositeAndReadbackAsync()
STDERR: #3 0x7f1b92bd9e29 blink::WebViewImpl::compositeAndReadbackAsync()
STDERR: #4 0x7f1b925b9779 test_runner::DumpPixelsAsync()
STDERR: #5 0x7f1b925d9014 test_runner::TestRunner::DumpPixelsAsync()
STDERR: #6 0x000000838d40 content::BlinkTestRunner::CaptureDumpContinued()
STDERR: #7 0x000000838756 content::BlinkTestRunner::OnLayoutDumpCompleted()
STDERR: #8 0x00000083639b content::BlinkTestRunner::CaptureDump()
STDERR: #9 0x000000835f59 content::BlinkTestRunner::TestFinished()
STDERR: #10 0x7f1b925d4b8a test_runner::TestRunner::NotifyDone()
STDERR: #11 0x7f1b925d2598 test_runner::TestRunnerBindings::NotifyDone()
STDERR: #12 0x7f1b925547e9 _ZN4base8internal13FunctorTraitsIMN11test_runner31AccessibilityControllerBindingsEFvvEvE6InvokeIPS3_JEEEvS5_OT_DpOT0_
STDERR: #13 0x7f1b92554761 _ZN4base8internal12InvokeHelperILb0EvE8MakeItSoIRKMN11test_runner31AccessibilityControllerBindingsEFvvEJPS5_EEEvOT_DpOT0_
STDERR: #14 0x7f1b925e3d86 _ZN4base8internal7InvokerINS0_9BindStateIMN11test_runner18TestRunnerBindingsEFvvEJEEEFvPS4_EE7RunImplIRKS6_RKSt5tupleIJEEJEEEvOT_OT0_NS_13IndexSequenceIJXspT1_EEEEOS8_
STDERR: #15 0x7f1b925e3cec _ZN4base8internal7InvokerINS0_9BindStateIMN11test_runner18TestRunnerBindingsEFvvEJEEEFvPS4_EE3RunEPNS0_13BindStateBaseEOS8_
STDERR: #16 0x7f1b925544f6 base::internal::RunMixin<>::Run()
STDERR: #17 0x7f1b925e3c23 _ZN3gin8internal7InvokerINS0_13IndicesHolderIJLm0EEEEJPN11test_runner18TestRunnerBindingsEEE18DispatchToCallbackEN4base8CallbackIFvS6_ELNS8_8internal8CopyModeE1ELNSB_10RepeatModeE1EEE
STDERR: #18 0x7f1b925e3ac9 gin::internal::Dispatcher<>::DispatchToCallback()
STDERR: #19 0x7f1b93d6491d v8::internal::FunctionCallbackArguments::Call()
STDERR: #20 0x7f1b93e24b8b v8::internal::(anonymous namespace)::HandleApiCallHelper<>()
STDERR: #21 0x7f1b93e23978 v8::internal::Builtin_Impl_HandleApiCall()
STDERR: #22 0x7f1b93e23561 v8::internal::Builtin_HandleApiCall()
STDERR: #23 0x239673b843a7 <unknown>
STDERR: 

(from https://build.chromium.org/p/chromium.webkit/builders/WebKit%20Linux%20Precise%20(dbg)/builds/698)

Assigning to wkorman who touched it last since jchaffraix has moved PAs.