add firefox extension template

externs/webextension_polyfill/geckoprofiler/ProfilerFeature.hx

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+package webextension_polyfill.geckoprofiler;
+
+typedef ProfilerFeature = String;

externs/webextension_polyfill/geckoprofiler/StartSettingsType.hx

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+package webextension_polyfill.geckoprofiler;
+
+typedef StartSettingsType = {
+	/**
+		The maximum size in bytes of the buffer used to store profiling data. A larger value allows capturing a profile that
+		covers a greater amount of time.
+	**/
+	var bufferSize : Float;
+	/**
+		The length of the window of time that's kept in the buffer. Any collected samples are discarded as soon as they are
+		older than the number of seconds specified in this setting. Zero means no duration restriction.
+		Optional.
+	**/
+	@:optional
+	var windowLength : Float;
+	/**
+		Interval in milliseconds between samples of profiling data. A smaller value will increase the detail of the profiles
+		captured.
+	**/
+	var interval : Float;
+	/**
+		A list of active features for the profiler.
+	**/
+	var features : Array<ProfilerFeature>;
+	/**
+		A list of thread names for which to capture profiles.
+		Optional.
+	**/
+	@:optional
+	var threads : Array<String>;
+};

externs/webextension_polyfill/geckoprofiler/Static.hx

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+package webextension_polyfill.geckoprofiler;
+
+typedef Static = {
+	/**
+		Starts the profiler with the specified settings.
+	**/
+	function start(settings:StartSettingsType):Void;
+	/**
+		Stops the profiler and discards any captured profile data.
+	**/
+	function stop():Void;
+	/**
+		Pauses the profiler, keeping any profile data that is already written.
+	**/
+	function pause():Void;
+	/**
+		Resumes the profiler with the settings that were initially used to start it.
+	**/
+	function resume():Void;
+	/**
+		Gathers the profile data from the current profiling session, and writes it to disk.
+		The returned promise resolves to a path that locates the created file.
+	**/
+	function dumpProfileToFile(fileName:String):Void;
+	/**
+		Gathers the profile data from the current profiling session.
+	**/
+	function getProfile():Void;
+	/**
+		Gathers the profile data from the current profiling session. The returned promise resolves to an array buffer that
+		contains a JSON string.
+	**/
+	function getProfileAsArrayBuffer():Void;
+	/**
+		Gathers the profile data from the current profiling session. The returned promise resolves to an array buffer that
+		contains a gzipped JSON string.
+	**/
+	function getProfileAsGzippedArrayBuffer():Void;
+	/**
+		Gets the debug symbols for a particular library.
+	**/
+	function getSymbols(debugName:String, breakpadId:String):Void;
+	/**
+		Fires when the profiler starts/stops running.
+	**/
+	var onRunning : webextension_polyfill.events.Event<(isRunning:Bool) -> Void>;
+};

externs/webextension_polyfill/geckoprofiler/Supports.hx

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+package webextension_polyfill.geckoprofiler;
+
+typedef Supports = String;