PsiCodegenPredictor.getFileForCodegenNamedClass() returns JetFile which
contains a declaration which will produce a class with a given name.
PsiCodegenPredictor.getFileForNamespacePartName() returns JetFile which
produces a namespace part with the given name.
BindingContextUtils.getContainingFile() returns JetFile which contains a
declaration which is matched to a given descriptor.
DescriptorUtils.findTopLevelParent() finds a top-level (i.e. its containing
declaration is NamespaceDescriptor) parent for a descriptor.
Also DescriptorUtils.isTopLevelFunction() is changed a little to accept not
only a function, but any descriptor
Alexander Udalov
880852861c