phantomjs wrapper: fix runfiles tree algorithm
phantomjs wrapper: fix runfiles tree algorithm

This fix failing test with bazel @HEAD.

Tested: 9d1e7dbfbb4d4ecaa4802d454ce979a1154fe638@HEAD: bazel clean --expunge && bazel test ...

SalzzZ/rules_closure,gramic/rules_closure,SalzzZ/rules_closure,jart/rules_closure,SalzzZ/rules_closure,jart/rules_closure,jart/rules_closure,bazelbuild/rules_closure,bazelbuild/rules_closure,SalzzZ/rules_closure,bazelbuild/rules_closure,jart/rules_closure,jart/rules_closure,SalzzZ/rules_closure,gramic/rules_closure,gramic/rules_closure,bazelbuild/rules_closure,gramic/rules_closure