FTRSwiftTest testButtonPressWithGREYAllOf is failing (but all the functional tests are passing, check to see if this is a test failure)

FTRSwiftTest testButtonPressWithGREYAllOf is failing but all the functional tests are passing, check to see if this is a test failure.

Logs:

All tests
Test Suite EarlGreyFunctionalSwiftTests.xctest started
FTRSwiftTests
✗ testButtonPressWithGREYAllOf, Exception: AssertionFailedException
✓ testChangingDatePickerToAFutureDate (4.093 seconds)
✓ testFastTyping (1.374 seconds)
✓ testInteractionWithALabelWithParentHidden (2.805 seconds)
✓ testOpeningView (1.099 seconds)
✓ testPossibleOpeningViews (3.623 seconds)
✓ testRotation (1.270 seconds)
✓ testStepperActionWithCondition (3.454 seconds)
✓ testSwiftCustomMatcher (0.062 seconds)
✓ testTyping (12.048 seconds)
✓ testTypingWithDeletion (6.590 seconds)
✓ testTypingWithError (16.336 seconds)
EarlGreyFunctionalSwiftTests.FTRSwiftTests
testButtonPressWithGREYAllOf, Exception: AssertionFailedException
/Users/travis/build/google/EarlGrey/Tests/FunctionalTests/Sources/FTRSwiftTests.swift:145
```
let matcher = grey_allOf([grey_text("Long Press"), grey_sufficientlyVisible()])
EarlGrey.select(elementWithMatcher: matcher).perform(grey_longPressWithDuration(1.0))
.assert(grey_notVisible())
```

Link to failing travis run: https://travis-ci.org/google/EarlGrey/jobs/241381376

Start with Tests/FunctionalTests/Sources/FTRSwiftTests.swift at line 145 and inspect testButtonPressWithGREYAllOf alongside the failing Travis log. Run the affected EarlGreyFunctionalSwiftTests target and determine whether the assertion reflects a test failure; done means the cause is identified and the test passes without breaking the other functional tests.

Written by the indexing model from the issue text.