feat(security): Automatic XSRF handling.

Automatically recognize XSRF protection cookies, and set a corresponding XSRF
header. Allows applications to configure the cookie names, or if needed,
completely override the XSRF request configuration by binding their own
XSRFHandler implementation.

Part of #8511.

modules/@angular/platform-browser/src/dom/dom_adapter.ts

@@ -152,4 +152,8 @@ export abstract class DomAdapter {
   abstract getAnimationPrefix(): string;
   abstract getTransitionEnd(): string;
   abstract supportsAnimation(): boolean;
+
+  abstract supportsCookies(): boolean;
+  abstract getCookie(name: string): string;
+  abstract setCookie(name: string, value: string);
 }