* Obey the excludeArgument parameter when checking JSX signature validity
* Fix conditional type extending any contextual types and accept baselines
* use flag check to also drop unknown from comparison for the same reason
* Slight refinement - make an intersection to ensure parameter constraints flow through contextual types when instantiated
* Format ternary more nicely
* Support 'isSourceFileFromExternalLibrary' for source files from '/// <reference types="" />''
* Calculate `isExternalLibraryImport` at the end
* Calculate isExternalLibraryImport with symlink path
* Add new special assignment kinds for recognizing Object.defineProperty calls
* Add support for prototype assignments, fix nits
* Fix code review comments
* Add test documenting behavior in a few more odd scenarios
In JS, when you assign `module.exports = exports` and the entire module is
wrapped in an IIFE, the resulting `export=` symbol, after following
aliases, is the module itself. This results in trying to merge the
file's exports with itself inside `getCommonJsExportEquals`, since it
thinks that it has found new exports, possibly in an object literal,
that need to be merged with the file's exports.
For example:
```js
(function() {
exports.a = 1
module.exports = exports
})()
```
1. Merge enum with expando.
2. Merge enum member with property assignment.
3. Merge interface-declared method declaration with
prototype-property-assignment method declaration.
The reason that the enum merges crash is that getTypeOfSymbol assumes
that symbol flags are (basically) mutually exclusive. This assumption is
shredded, badly, for JS merges.
One fix is to drop the assumption of exclusivity and instead order cases
by least to most likely. This has the highest chance of working, but is
also slow, since you would prefer to order cases by most likely *first*,
not *last*.
The other fix, which is what I did here, is to add a last-chance
re-dispatch at the bottom of
`getTypeOfVariableOrParameterOrPropertyWorker`. This dispatch uses the
valueDeclaration instead of the symbol flags.
When contextual type doesnt find property in unit type, use the index signature from unit type(fix the incorrectly used union type to get the signature)
* Unify JSX Call Checking Codepaths
* Add tests for fixed issues
* Fix lint, move all error checking into the only-run-once resolveSignature call
* Remove unused (unreachable?) code path
* Consolidate a little more duplicated logic into signature checking
* Fix#19775 a bit more
* Cosmetic changes from CR
