5f66068c26516317052b0a33fd4311a194fccae7  [Site Isolation] Dragged selection in a scrolled cross-origin iframe appears at the top of the page

Classified as not security-relevant.
Triage note: DragController switches contentsToRootView to contentsToMainFrameView and WebViewImpl.mm inlines the async convertPointToMainFrameCoordinates callback into a synchronous path; coordinate-space plumbing/refactor, no 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), uaf_lifetime (+4.75), large_churn (-2.0)