a8808be837b72d0ac663176ace9b871dd8005693  [Image Redux] Bundle the state SVGImage::draw() sets on its document into a struct

Classified as not security-relevant.
Triage note: SVGImage refactor consolidating per-draw container size, fragment URL, link parameters and invert-content into a single DocumentState computed in documentStateForDraw and applied once in applyDocumentState. Rendering correctness/dedup, no security bug (FIXME 322833 remains).
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 (+4.87), null_guard (+1.95), area:Source/WebCore/svg (+2.0)