LazyBridgeRegistry<K> class

A key → BridgedClass map whose entries may be stored as deferred thunks rather than pre-built classes.

Step #3 of the import-optimization plan (substrate for the generator's lazy emission, plan step #17). operator [] resolves a thunk on first access and memoizes the built BridgedClass, so a heavy class body (its seven member maps and all adapter closures) is constructed at most once. containsKey / keys / length only consult the thunk keys, so probing for a name never forces a build.

Used both name-keyed (K = String, lexical lookup) and type-keyed (K = Type, native-object resolution). Today every entry is a trivial () => alreadyBuiltClass thunk (registration still hands over built classes — behaviour unchanged); once the generator emits genuinely deferred thunks, the heavy body is built only when the name/type is first touched during interpretation.

Mirror of the same class in tom_d4rt environment.dart.

Public so the D4rtRunner-level registries (_bridgedDefLookupByType and the pooled _PackageBridgeBundle.bridgedDefLookupByType) can be thunk-backed too — the generator's lazy emission (import-optimization plan step #17) stores a Type → thunk entry at registration time without building the class.