fix(browser): use /devtools/page endpoint for all target types including iframes

[I1Kuz]

Description

Problem

When Chrome creates targets for cross-origin iframes (Out-Of-Process Iframes / OOPIF), Browser._handle_target_update receives a cdp.target.TargetCreated event where target_info.type_ == "iframe".

The WebSocket connection URL was constructed as:

f"/devtools/{target_info.type_ or 'page'}"

This evaluated to ws://<host>:<port>/devtools/iframe/<target_id>. Attempting to connect to this target resulted in:

websockets.exceptions.InvalidStatus: server rejected WebSocket connection: HTTP 404

Chrome DevTools HTTP server only accepts connections under /devtools/page/<target_id> for all target types (as noted in the author's comment on that line, and as already implemented in Browser.update_targets).

Solution

• Changed the WebSocket URL in Browser._handle_target_update to always use /devtools/page/<target_id>.
• Allows Tab instances representing iframe targets to successfully connect via WebSocket and interact with elements inside cross-origin iframes.

Also consider exposing a property:

@property
def iframes(self) -> List[tab.Tab]:
    return [item for item in self.targets if getattr(item, "type_", None) == "iframe"]

and searching those targets in select_all(include_frames=True) when content_document is null due to cross-origin isolation.

Pre-merge Checklist

• I have described my change in the section above.
• I have ran the ./scripts/format.sh and ./scripts/lint.sh scripts. My code is properly formatted and has no linting errors.
• I have ran uv run pytest and ensured all tests pass.
• I have added my change to CHANGELOG.md under the [Unreleased] section.