TypeError: "capsObject.toJSON" is not a function with Protractor >=2.4.0

[cyparu]

Documented in related issue angular/protractor#2592:

I'm playing with Benchpress demo that works just fine for Protractor < 2.4.0 but with higher versions (I've tested with 2.4.0 & 2.5.0) I got this error:

 1) deep tree baseline should be fast!
  Message:
    Failed: TypeError: capsObject.toJSON is not a function
  Stack:
    Error: TypeError: capsObject.toJSON is not a function
        at proxyDone.fail (X:\perf-tests\benchpress-tree\node_modules\protractor\node_modules\jasminewd2\index.js:89:34)
        at promiseReactionJob (X:\perf-tests\benchpress-tree\node_modules\benchpress\index.js:8379:27)
        at Immediate._onImmediate (X:\perf-tests\benchpress-tree\node_modules\benchpress\index.js:8392:11)
    From: Task: Run it("should be fast!") in control flow
        at Object. (X:\perf-tests\benchpress-tree\node_modules\protractor\node_modules\jasminewd2\index.js:81:14)
        at attemptAsync (X:\perf-tests\benchpress-tree\node_modules\jasmine-core\lib\jasmine-core\jasmine.js:1819:24)
        at QueueRunner.run (X:\perf-tests\benchpress-tree\node_modules\jasmine-core\lib\jasmine-core\jasmine.js:1774:9)
        at X:\perf-tests\benchpress-tree\node_modules\jasmine-core\lib\jasmine-core\jasmine.js:1801:16
        at X:\perf-tests\benchpress-tree\node_modules\jasmine-core\lib\jasmine-core\jasmine.js:1745:9
        at X:\perf-tests\benchpress-tree\node_modules\protractor\node_modules\jasminewd2\index.js:18:5
        at Array.forEach (native)
    From asynchronous test:
    Error
        at Suite. (X:\perf-tests\benchpress-tree\tree_benchmark.spec.js:16:3)
        at addSpecsToSuite (X:\perf-tests\benchpress-tree\node_modules\jasmine-core\lib\jasmine-core\jasmine.js:743:25)
        at Env.describe (X:\perf-tests\benchpress-tree\node_modules\jasmine-core\lib\jasmine-core\jasmine.js:713:7)
        at jasmineInterface.describe (X:\perf-tests\benchpress-tree\node_modules\jasmine-core\lib\jasmine-core\jasmine.js:3219:18)
        at Object. (X:\perf-tests\benchpress-tree\tree_benchmark.spec.js:15:1)