Fixes illegal processing of DUP2, DUP_X1, DUP_X2m, DUP2_X2 instructions.

Makes more fancy list of missing items

pom.xml

@@ -22,6 +22,7 @@
   </modules>
 
   <build>
+    <pluginManagement>
       <plugins>
         <plugin>
           <groupId>org.apache.maven.plugins</groupId>
@@ -33,6 +34,7 @@
           </configuration>
         </plugin>
       </plugins>
+    </pluginManagement>
   </build>
 
   <profiles>

teavm-core/src/main/java/org/teavm/dependency/DependencyChecker.java

@@ -355,24 +355,19 @@ public class DependencyChecker implements DependencyInformation {
         if (missingClasses.isEmpty() && missingMethods.isEmpty() && missingFields.isEmpty()) {
             return;
         }
-        StringBuilder sb = new StringBuilder();
-        if (!missingClasses.isEmpty()) {
-            sb.append("Missing classes:\n");
-            for (String cls : missingClasses) {
-                sb.append("  ").append(cls).append("\n");
-            }
-        }
-        if (!missingMethods.isEmpty()) {
-            sb.append("Missing methods:\n");
+        List<String> items = new ArrayList<>();
+        items.addAll(missingClasses);
         for (MethodReference method : missingMethods) {
-                sb.append("  ").append(method).append("\n");
+            items.add(method.toString());
         }
-        }
-        if (!missingMethods.isEmpty()) {
-            sb.append("Missing fields:\n");
         for (FieldReference field : missingFields) {
-                sb.append("  ").append(field).append("\n");
+            items.add(field.toString());
         }
+        Collections.sort(items);
+        StringBuilder sb = new StringBuilder();
+        sb.append("Can't compile due to the following items missing:\n");
+        for (String item : items) {
+            sb.append("  ").append(item).append("\n");
         }
         throw new IllegalStateException(sb.toString());
     }

teavm-core/src/main/java/org/teavm/model/FieldReference.java

@@ -52,4 +52,9 @@ public class FieldReference {
         FieldReference other = (FieldReference)obj;
         return className.equals(other.className) && fieldName.equals(other.fieldName);
     }
+
+    @Override
+    public String toString() {
+        return className + "." + fieldName;
+    }
 }