Correct Jest toBeCloseTo signature

In Jest .toBeCloseTo's second parameter is optional with a default of 5.

See:
https://facebook.github.io/jest/docs/api.html#tobeclosetonumber-numdigits

This updates the type definition to make this parameter optional as
well.

jest/index.d.ts

@@ -117,7 +117,7 @@ declare namespace jest {
         toBe(expected: any): void;
         toBeCalled(): void;
         toBeCalledWith(...args: any[]): void;
-        toBeCloseTo(expected: number, delta: number): void;
+        toBeCloseTo(expected: number, delta?: number): void;
         toBeDefined(): void;
         toBeFalsy(): void;
         toBeGreaterThan(expected: number): void;

jest/jest-tests.ts

@@ -147,6 +147,10 @@ describe('compartion', function () {
     it('works sanely with simple decimals', function () {
         expect(0.2 + 0.1).toBeCloseTo(0.3, 5);
     });
+
+    it('works sanely with simple decimals and the default delta', function () {
+        expect(0.2 + 0.1).toBeCloseTo(0.3);
+    });
 });
 
 describe('toThrow API', function () {