Add Flow type definitions

Author: dgraham

include-fragment-element.js.flow

@@ -0,0 +1,12 @@
+/* @flow */
+
+declare class IncludeFragmentElement extends HTMLElement {
+  get data(): Promise<string>;
+  get src(): string;
+  set src(url: string): void;
+  fetch(request: Request): Promise<Response>;
+}
+
+declare module 'include-fragment-element' {
+  declare export default typeof IncludeFragmentElement
+}