A partial Scala.js classpath is a collection of:
PartialClasspaths can be combined (using merge) and eventually resolved
to a CompleteIRClasspath
Merges another PartialClasspath with this one.
Merges another PartialClasspath with this one. This means:
Construct a IRClasspath out of this PartialClasspath by
resolving library dependencies (and failing if they are not met)
(Since version 0.6.3) Use the version with manifestFilter instead