Enter the destination context scope before creating the VideoFrame V8
wrapper, matching the sibling Element and Blob branches. Without this,
ScriptState::ForCurrentRealm resolved to the calling context instead of
the target context, producing an incorrect wrapper.
Also switch to ScriptState::From with an explicit context argument to
make the intent clearer.
Adds spec coverage for VideoFrame crossing the bridge in both
directions and adds VideoFrame to the existing prototype checks.
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