This adds a way to run only a subset of the tests.
(The new flags do the same thing as 'pub run test'.)

* increase the timeout for service discovery

* remove the timeout for discovering service ports

Remove terminating semicolons; they are causing an "code inspection warning" in Android Studio:

```
This inspection reports redundant semicolon (';') token which is not required in Kotlin and may be removed.
```

* Guess sign with the first certificate when multiple are available in machine mode

* review

In the case where the CocoaPods 'pod install' step fails, emit its
stdout to provide any potentially-useful error messages to the user.

This reverts commit b800654a.

This time, do so in Travis' sudo-enabled environment,
which is said to be less prone to networking issues.
It also means we'll run in an env with 7.5GB of RAM
instead of 4GB or RAM (at the cost of about 45 seconds
of extra boot-up time).

https://github.com/flutter/flutter/issues/10940

This reverts commit aa904a58.

Fixes #10940

* Switch existings tests to use equalsIgnoringHashCodes and add more tests.

* Use defaultTargetPlatform instead of Platform.operatingSystem for ImageProvider.
Add convenience helper to make it easier to display a short string for
an enums value.

* Add comment linking to issue.

And fix a typo in a test description.

Previously, xcodeMajorVersion and xcodeMinorVersion returned null unless
xcodeVersionSatisfactory had been called first. We now compute them on
demand, and cache the resultant values.

Also, correct an existing test description.

Applies comments I missed from https://github.com/flutter/flutter/pull/10904.

* Prefix and Suffix support for TextFields

* Adding Tests

* Removing spurious newline.

* Fixing a small problem with the test

* Code review changes

* Code Review Changes

* Review Changes

* Export the new StrokeJoin enum

* Added example for line styles, and enabled line join styles.

* Reverting inadvertent change to main.dart.

* Updated due to code review of engine code

* Removed example.

...so that we can compare it to the not-working test next to it.

1. Run all Xcode tool invocations through ProcessManager, which allows
us to mock out failures, etc. for tests.

2. Add said tests.