This fixes the last of our Javadoc warnings without creating a
circular dependency between ":com.ibm.wala.cast:javadoc" and
":com.ibm.wala.cast.js:javadoc". Fixes#4, wherein more details about
this tricky dependency challenge can be found.
I was confused about the differences among:
srcDir 'foo'
srcDirs ['foo']
srcDirs = ['foo']
As it turns out, the first two append to the set of source
directories, while the last replaces this set entirely. I generally
want replacement, since WALA's current directory layout never matches
Gradle's assumed defaults.