Summary:
I did some stylistic changes to the Objective-C unit tests for the following reasons:
- When an equality assert fails, the error messages reads as if the value we are testing is the first argument and the value we expect is the second argument. To improve the readability of test messages, I made sure all `XCTAssertEqual` and `XCTAssertNotEqual` have the arguments in the correct order.
- Because failing equality asserts already comes with a detailed message including the value tested and the expected value, I rewrote several truth asserts on `CGSizeEqual` to two equality asserts on the width and height: when those fail, the error message are clearer.
Closes https://github.com/facebook/yoga/pull/351
Reviewed By: emilsjolander
Differential Revision: D4454484
Pulled By: dshahidehpour
fbshipit-source-id: 0c1295a4a7e8477eacfb3f4ef6648984fd102a51