Non-exported classes in type declaration files leaking value names

**TypeScript Version:** 3.5.2 **Search Terms:** ambient module declaration export declare class type name **Code** In a file called `classes.d.ts`: ```ts declare class A {} export declare class B extends A {} ``` In a file called `test.js`: ```js let a = require('classes').A; ``` In a file called `test.ts`: ```ts import { A } from './types/classes'; ``` **_[NEW]_ Assumptions:** The following is a list of assumptions I had when originally opening this issue: 1. Type Declaration Files work like modules: once you use `import` or `export` [on a top-level declaration], only explicitly `export`ed declarations are visible externally. 1. Type names declared in a Declaration File are always accessible via `import` types (at least those that are _used_ by `export`ed types. - E.g. `export class B extends A` exports the type names `A` and `B`, even if `A` was not directly `export`ed. 1. Value names declared in a module-style Declaration File (see `#1` above) are only accessible if explicitly `export`ed. These assumptions are the result of reading the [documentation](https://www.typescriptlang.org/docs/handbook/declaration-files/deep-dive.html) and working with declaration files. Note that the documentation **_does not_** mention: 1. _All_ declarations in a declaration file are [implicitly exported](https://github.com/microsoft/TypeScript/issues/32182#issuecomment-507006868). 1. Special [and undocumented?] `export {};` syntax causes only explicitly `export`ed declarations to be available by consumers of the declaration file. I list them here to provide context for the Expected Behavior section. **Expected behavior:** In both cases , an Error that name 'A' could be found in module 'classes'. I expect in this case that TypeScript is capable of resolving the following from the declaration file: 1. The [**Value**](https://www.typescriptlang.org/docs/handbook/declaration-files/deep-dive.html#values) "B". 1. The [**Types**](https://www.typescriptlang.org/docs/handbook/declaration…