Class<haxe.macro.Compiler> has no field setCustomJSGenerator

Somehow the #5172 test started failing in CI.

[Build log](https://dev.azure.com/HaxeFoundation/GitHubPublic/_build/results?buildId=326&view=logs&j=d81420a3-bf30-5d37-575b-fa6a2af01070&t=cc110ab7-c476-5aac-3bed-0ec1854cadd7&l=53):
```
2019-07-15T22:50:14.5927526Z Command: haxe [build.hxml]
2019-07-15T22:50:28.3324791Z utest/ui/text/PrintReport.hx:52:
2019-07-15T22:50:28.3324914Z assertations: 1096
2019-07-15T22:50:28.3325116Z successes: 1095
2019-07-15T22:50:28.3325472Z errors: 1
2019-07-15T22:50:28.3326876Z failures: 0
2019-07-15T22:50:28.3327612Z warnings: 0
2019-07-15T22:50:28.3327840Z execution time: 12.45
2019-07-15T22:50:28.3328040Z
2019-07-15T22:50:28.3328275Z results: SOME TESTS FAILURES (success: false)
2019-07-15T22:50:28.3328483Z cases.Issue5172
2019-07-15T22:50:28.3328662Z test: ERROR ...E
2019-07-15T22:50:28.3329113Z HaxeInvocationException(D:\a\1\s\win64Binaries\haxe\std/haxe/macro/ExampleJSGenerator.hx:255: characters 3-32 : Class has no field setCustomJSGenerator
2019-07-15T22:50:28.3331276Z src/DisplayTestContext.hx:27: characters 26-36 : Unknown identifier : haxeserver
2019-07-15T22:50:28.3331632Z D:\a\1\s\win64Binaries\haxe\std/jvm/annotation/ClassReflectionInformation.hx:28: characters 46-77 : Type not found : java.lang.annotation.Annotation
2019-07-15T22:50:28.3331866Z
2019-07-15T22:50:28.3332213Z , test, [--display,src/cases/Issue5172.hx@69@usage], package cases;
2019-07-15T22:50:28.3332359Z
2019-07-15T22:50:28.3332695Z class Main {
2019-07-15T22:50:28.3332869Z static function main() {
2019-07-15T22:50:28.3333595Z for (i in 0...10) {
2019-07-15T22:50:28.3333909Z i;
2019-07-15T22:50:28.3334446Z }
2019-07-15T22:50:28.3335438Z }
2019-07-15T22:50:28.3336930Z }
2019-07-15T22:50:28.3340178Z ])
2019-07-15T22:50:28.3344683Z Called from local function #1 (src/cases/Issue5172.hx line 13 column 2)
2019-07-15T22:50:28.3346599Z Called from cases.Issue5172.test (src/cases/Issue5172.hx line 17 column 26)
2019-07-15T22:50:28.3348377Z Called from DisplayTestContext.usage (src/DisplayTestContext.hx line 76 column 27)
2019-07-15T22:50:28.3480379Z Called from DisplayTestContext.callHaxe (src/DisplayTestContext.hx line 109 column 4)
2019-07-15T22:50:28.3483239Z
2019-07-15T22:50:28.3504550Z Command exited with 1 in 14s: haxe [build.hxml]
```