240e5121f5b0a30128a19b86fdd4e25ed0159b09  [Site Isolation] Web Inspector: Documents that become current while a same-process frame is paused are not held

Classified as not security-relevant.
Triage note: Extracts FrameDebugger::setJavaScriptPausedInAllPages/setJavaScriptPaused into a new DebuggerSuspensionController wired through PageInspectorController; inspector/devtools-only refactor of how a paused debugger holds documents, no attacker-reachable bug addressed.
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), msg_soft (+1.0), area:Source/WebCore/dom (+2.0), large_churn (-2.0)