As you can see here:
the Plugin’s name is defined as intentPlugin:
<js-module src="www/intentPlugin.js" name="intentPlugin">
<clobbers target="intentPlugin" />
Try the following:
declare var intentPlugin: any;
I think the declaration has to go after the imports, but before the class or like me: in a separate file ‘declaration.ts’.
Then try to use it, but you have to check your Spelling, because without wrapper your wrapper could not provide autocomplete functions.