Improve ol.structs.LRUCache type annotation
Add missing array type in ol.structs.LRUCache#getValues
Merge pull request #2630 from fredj/misc

Improve ol.structs.LRUCache type annotation
Add @extends annotations to generated externs
Do not extend goog.* types
Walk up the inheritance chain to an exportable constructor
Add base classes to info.json and generated externs

This ensures that the inheritance chain is intact, even if the base
class is not exportable.