test(test/reporters/base.spec.js): Fix Base reporter test failure due…

… to timeout

The `Base` reporter's specification verifies reporter can interpret Chai custom error messages. This
test takes ~480ms (lightly loaded CPU), which is _way_ too close to the 500ms timeout. Change
doubles this timeout.

#3524

test/reporters/base.spec.js

@@ -312,6 +312,7 @@ describe('Base reporter', function() {
   });
 
   it('should interpret Chai custom error messages', function() {
+    this.timeout(1000);
     var chaiExpect = require('chai').expect;
     try {
       chaiExpect(43, 'custom error message').to.equal(42);