src/utils/annotateWithScopes.js/Scope/addDeclaration
class Scope:	addDeclaration ( node ) {
		if ( node.kind === 'var' && !this.block && this.parent ) {
			this.parent.addDeclaration( node );
		} else if ( node.type === 'VariableDeclaration' ) {
			node.declarations.forEach( declarator => {
				extractNames( declarator.id ).forEach( name => {
					this.declarations.add( name );
				});
			});
		} else {
			this.declarations.add( node.id.name );
		}
	}