ExtractDomain mistakenly checks source first then url

[borislin]

Describe the bug
ExtractDomain mistakenly checks source first then url.

To Reproduce
Steps to reproduce the behavior:

1. Fix unit test by updating the data2 variable in ExtractDomainTest to be the following:
   private val data2 = Seq.newBuilder.+=( (index, "http://www.umiacs.umd.edu/~jimmylin/", umiacs), ("https://github.com/lintool", "http://www.umiacs.umd.edu/~jimmylin/", "github.com"), (index, "https://github.com/lintool", "github.com")).result()
2. Run mvn clean package
3. See error and build fails

Expected behavior
mvn clean package should not produce any error after fixing the unit test ExtractDomainTest. Build should succeed.

Environment information

• AUT version: HEAD
• OS: tuna
• Java version: Java 8