Actually use java 11, custom flags to let it compile in maven

Author: niloc132

j2cl-maven-plugin/src/it/java11-project-and-emul/emul/pom.xml

@@ -28,8 +28,12 @@
                     <artifactId>maven-compiler-plugin</artifactId>
                     <version>3.6.1</version>
                     <configuration>
-                        <source>1.8</source>
-                        <target>1.8</target>
+                        <compilerArgs>
+                            <arg>--patch-module</arg>
+                            <arg>java.base=.</arg>
+                            <arg>--add-reads</arg>
+                            <arg>java.base=ALL-UNNAMED</arg>
+                        </compilerArgs>
                     </configuration>
                 </plugin>
             </plugins>

j2cl-maven-plugin/src/it/java11-project-and-emul/emul/src/main/java/java/io/EOFException.java

@@ -30,6 +30,6 @@ public EOFException() {
 
     public EOFException(String s) {
         super(s);
-        String string = s + "hello";
+        var string = s + "hello";
     }
 }