Editing: Make the |EditingState*| argument of CompositeEditCommand::removeNode mandatory.

This CL doesn't introduce new ASSERT_NO_EDITING_ABORTs except cases where node
removal won't dispatch synchronous events.

This CL has no tests.  We're not sure if this CL makes user-visible behavior
changes.  The purpose of this CL is to reduce ClusterFuzz crashes in the future.

BUG=586846

Review URL: https://codereview.chromium.org/1695153002

Cr-Commit-Position: refs/heads/master@{#375417}
17 files changed