add missing externs to repo

externs/webextension_polyfill/storage/LocalStorageArea.hx

@@ -0,0 +1,30 @@
+package webextension_polyfill.storage;
+
+typedef LocalStorageArea = {
+	/**
+		The maximum amount (in bytes) of data that can be stored in local storage, as measured by the JSON stringification of
+		every value plus every key's length. This value will be ignored if the extension has the <code>unlimitedStorage</code>
+		permission. Updates that would cause this limit to be exceeded fail immediately and set $(ref:runtime.lastError).
+	**/
+	var QUOTA_BYTES : Int;
+	/**
+		Gets one or more items from storage.
+	**/
+	function get(?keys:ts.AnyOf3<String, Array<String>, haxe.DynamicAccess<Dynamic>>):js.lib.Promise<haxe.DynamicAccess<Dynamic>>;
+	/**
+		Sets multiple items.
+	**/
+	function set(items:haxe.DynamicAccess<Dynamic>):js.lib.Promise<ts.Undefined>;
+	/**
+		Removes one or more items from storage.
+	**/
+	function remove(keys:ts.AnyOf2<String, Array<String>>):js.lib.Promise<ts.Undefined>;
+	/**
+		Removes all items from storage.
+	**/
+	function clear():js.lib.Promise<ts.Undefined>;
+	/**
+		Fired when one or more items change.
+	**/
+	var onChanged : webextension_polyfill.events.Event<(changes:StorageAreaOnChangedChangesType) -> Void>;
+};