Add missing Date to cy.clock typescript def (#4106)

* add missing option from clock tsdef

* add type test for cy.clock with Date

cli/types/index.d.ts

@@ -510,7 +510,7 @@ declare namespace Cypress {
      *    // keep current date but override "setTimeout" and "clearTimeout"
      *    cy.clock(null, ['setTimeout', 'clearTimeout'])
      */
-    clock(now: number, functions?: Array<'setTimeout' | 'clearTimeout' | 'setInterval' | 'clearInterval'>, options?: Loggable): Chainable<Clock>
+    clock(now: number, functions?: Array<'setTimeout' | 'clearTimeout' | 'setInterval' | 'clearInterval' | 'Date'>, options?: Loggable): Chainable<Clock>
     /**
      * Mocks global clock and all functions.
      *

cli/types/tests/cypress-tests.ts

@@ -271,3 +271,6 @@ namespace CypressTriggerTests {
       arbitraryProperty: 0
     })
 }
+
+const now = new Date(2019, 3, 2).getTime()
+cy.clock(now, ['Date'])