Wrong invalid highlighting of double escaped patterns in key bindings

[deathaxe]

	{ "keys": ["alt+b"], "command": "insert_snippet", "args": {"contents": "**${SELECTION/^\\*\\*|^__|\\*\\*$|__$//g}**"}, "context":
		[
			{ "key": "selector", "operator": "equal", "operand": "text.html.markdown - markup.bold - markup.bold_italic", "match_all": true },
			{ "key": "setting.mde.bold_marker_asterisk", "operator": "equal", "operand": true },
			{ "key": "selection_empty", "operator": "equal", "operand": false, "match_all": true },
			{ "key": "preceding_text", "operator": "not_regex_contains", "operand": "\\*$|__$", "match_all": true },
			{ "key": "following_text", "operator": "not_regex_contains", "operand": "^\\*|^__", "match_all": true }
		]
	},

[keith-hall]

potentially related: https://github.com/sublimehq/sublime_text/issues/1597