c0a49688cb186d90984cc82b3b45259088e1cf77  [list-marker] Give every outside list marker its content as renderers instead of hand-drawing the text and the image

Classified as not security-relevant.
Triage note: Large refactor of RenderListOutsideMarker/list-marker layout: removes hand-drawn text and bidi-resolution paths (textNeedsBidiResolution, needsContentContainer, relativeMarkerRect), unifies markers through a content container and introduces IsListMarkerImage. Rendering refactor/feature rework with no identified memory-safety or logic security bug.
This commit was flagged by the signal scorer and reviewed by AI (not a human). It is listed only so the triage is auditable; there is no root-cause analysis because this is not a vulnerability fix.

Structural signals: smartptr_member_added (+6.47), null_guard (+2.59), area:Source/WebCore/layout (+2.0), large_churn (-2.0)