Merge pull request #9647 from dotty-staging/add-windows-ci

Add windows CI

Author: liufengyun

Diff for: .appveyor.yml

@@ -0,0 +1,18 @@
+version: '{build}'
+os: Windows Server 2012
+environment:
+  global:
+    NODEJS_VERSION: "12"
+matrix:
+  fast_finish: true
+
+init:
+  - ps: Install-Product node $env:NODEJS_VERSION
+  - cmd: choco install sbt
+  - cmd: refreshenv
+  - cmd: SET "SBT_OPTS=-Xmx4g -Xms4m"
+build_script:
+  - cmd: sbt dotty-bootstrapped/compile
+test_script:
+  - cmd: sbt "dotty-bootstrapped/dotc tests\pos\HelloWorld.scala"
+  - cmd: sbt sjsJUnitTests/test