Add source code compatibility check CI

Author: kateinoigakukun

.github/workflows/compatibility.yml

@@ -0,0 +1,20 @@
+name: Check compatibility
+on: [push, pull_request]
+jobs:
+  test:
+    name: Check source code compatibility
+    runs-on: Ubuntu-18.04
+    steps:
+      - name: Checkout
+        uses: actions/checkout@master
+        with:
+          fetch-depth: 1
+      - name: Run Test
+        run: |
+          git clone https://github.com/kylef/swiftenv.git ~/.swiftenv
+          export SWIFTENV_ROOT="$HOME/.swiftenv"
+          export PATH="$SWIFTENV_ROOT/bin:$PATH"
+          eval "$(swiftenv init -)"
+          make bootstrap
+          cd Example
+          swift build --triple wasm32-unknonw-wasi

Example/JavaScriptKitExample/Sources/JavaScriptKitExample/main.swift

@@ -1,7 +1,7 @@
 import JavaScriptKit
 
-let alert = JSObjectRef.global.alert.function!
-let document = JSObjectRef.global.document.object!
+let alert = JSObject.global.alert.function!
+let document = JSObject.global.document.object!
 
 let divElement = document.createElement!("div").object!
 divElement.innerText = "Hello, world"
@@ -10,6 +10,7 @@ _ = body.appendChild!(divElement)
 
 let buttonElement = document.createElement!("button").object!
 buttonElement.innerText = "Click me!"
+let onClickListener = 
 buttonElement.onclick = .function { _ in
     alert("Swift is running on browser!")
 }