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

Makes more fancy list of missing items

pom.xml

@@ -22,17 +22,19 @@
   </modules>
 
   <build>
-    <plugins>
-      <plugin>
-        <groupId>org.apache.maven.plugins</groupId>
-        <artifactId>maven-compiler-plugin</artifactId>
-        <version>2.5.1</version>
-        <configuration>
-          <source>1.7</source>
-          <target>1.7</target>
-        </configuration>
-      </plugin>
-    </plugins>
+    <pluginManagement>
+      <plugins>
+        <plugin>
+          <groupId>org.apache.maven.plugins</groupId>
+          <artifactId>maven-compiler-plugin</artifactId>
+          <version>2.5.1</version>
+          <configuration>
+            <source>1.7</source>
+            <target>1.7</target>
+          </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;
         }
+        List<String> items = new ArrayList<>();
+        items.addAll(missingClasses);
+        for (MethodReference method : missingMethods) {
+            items.add(method.toString());
+        }
+        for (FieldReference field : missingFields) {
+            items.add(field.toString());
+        }
+        Collections.sort(items);
         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");
-            for (MethodReference method : missingMethods) {
-                sb.append("  ").append(method).append("\n");
-            }
-        }
-        if (!missingMethods.isEmpty()) {
-            sb.append("Missing fields:\n");
-            for (FieldReference field : missingFields) {
-                sb.append("  ").append(field).append("\n");
-            }
+        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;
+    }
 }