Bundle the required DOM types (#93)

Closes #92

source/index.ts

@@ -1,5 +1,46 @@
 /// <reference lib="esnext"/>
-/// <reference lib="dom"/>
+
+/* -- Copy-pasted DOM types -- */
+// TODO: Remove these when https://github.com/microsoft/TypeScript/issues/33111 is fixed.
+interface URLSearchParams {
+	append(name: string, value: string): void;
+	delete(name: string): void;
+	get(name: string): string | null;
+	getAll(name: string): string[];
+	has(name: string): boolean;
+	set(name: string, value: string): void;
+	sort(): void;
+	forEach(callbackfn: (value: string, key: string, parent: URLSearchParams) => void, thisArg?: any): void;
+}
+
+declare var URLSearchParams: { // eslint-disable-line no-var
+	prototype: URLSearchParams;
+	new(init?: string[][] | Record<string, string> | string | URLSearchParams): URLSearchParams;
+};
+
+interface URL {
+	hash: string;
+	host: string;
+	hostname: string;
+	href: string;
+	readonly origin: string;
+	password: string;
+	pathname: string;
+	port: string;
+	protocol: string;
+	search: string;
+	readonly searchParams: URLSearchParams;
+	username: string;
+	toJSON(): string;
+}
+
+declare var URL: { // eslint-disable-line no-var
+	prototype: URL;
+	new(url: string, base?: string | URL): URL;
+	createObjectURL(object: any): string;
+	revokeObjectURL(url: string): void;
+};
+/* ---- */
 
 // TODO: Use the `URL` global when targeting Node.js 10
 const URLGlobal = typeof URL === 'undefined' ? require('url').URL : URL;