Fix for resolving interface constructors in factory, issue 521.

compiler/java/com/google/dart/compiler/resolver/SyntheticDefaultConstructorElement.java

Index: compiler/java/com/google/dart/compiler/resolver/SyntheticDefaultConstructorElement.java
diff --git a/compiler/java/com/google/dart/compiler/resolver/SyntheticDefaultConstructorElement.java b/compiler/java/com/google/dart/compiler/resolver/SyntheticDefaultConstructorElement.java
new file mode 100644
index 0000000000000000000000000000000000000000..ee0d77581c045eeca3a0027da754490091d324cb
--- /dev/null
+++ b/compiler/java/com/google/dart/compiler/resolver/SyntheticDefaultConstructorElement.java
@@ -0,0 +1,129 @@
+// Copyright (c) 2011, the Dart project authors.  Please see the AUTHORS file
+// for details. All rights reserved. Use of this source code is governed by a
+// BSD-style license that can be found in the LICENSE file.
+package com.google.dart.compiler.resolver;
+
+import com.google.dart.compiler.ast.DartLabel;
+import com.google.dart.compiler.ast.DartMethodDefinition;
+import com.google.dart.compiler.ast.DartNode;
+import com.google.dart.compiler.ast.Modifiers;
+import com.google.dart.compiler.type.DynamicType;
+import com.google.dart.compiler.type.FunctionType;
+import com.google.dart.compiler.type.Type;
+import com.google.dart.compiler.type.TypeVariable;
+import com.google.dart.compiler.type.Types;
+
+import java.util.Collections;
+import java.util.List;
+
+/**
+ * {@link ConstructorElement} for implicit default constructor.
+ */
+public class SyntheticDefaultConstructorElement implements ConstructorElement {
+  private final DartMethodDefinition method;
+  private final ClassElement enclosingClass;
+  private final FunctionType functionType;
+
+  public SyntheticDefaultConstructorElement(DartMethodDefinition method,
+      ClassElement enclosingClass,
+      CoreTypeProvider typeProvider) {
+    this.method = method;
+    this.enclosingClass = enclosingClass;
+    this.functionType =
+        Types.makeFunctionType(
+            null,
+            typeProvider.getFunctionType().getElement(),
+            getParameters(),
+            typeProvider.getDynamicType(),
+            Collections.<TypeVariable>emptyList());
+  }
+
+  @Override
+  public String getOriginalSymbolName() {
+    return getName();
+  }
+
+  @Override
+  public DartNode getNode() {
+    return method;
+  }
+
+  @Override
+  public void setNode(DartLabel node) {
+  }
+
+  @Override
+  public boolean isDynamic() {
+    return false;
+  }
+
+  @Override
+  public Type getType() {
+    return functionType;
+  }
+
+  @Override
+  public String getName() {
+    return "";
+  }
+
+  @Override
+  public Modifiers getModifiers() {
+    return Modifiers.NONE;
+  }
+
+  @Override
+  public ElementKind getKind() {
+    return ElementKind.CONSTRUCTOR;
+  }
+
+  @Override
+  public EnclosingElement getEnclosingElement() {
+    return enclosingClass;
+  }
+
+  @Override
+  public boolean isStatic() {
+    return false;
+  }
+
+  @Override
+  public boolean isConstructor() {
+    return true;
+  }
+
+  @Override
+  public Type getReturnType() {
+    return functionType.getReturnType();
+  }
+
+  @Override
+  public List<VariableElement> getParameters() {
+    return Collections.emptyList();
+  }
+
+  @Override
+  public FunctionType getFunctionType() {
+    return functionType;
+  }
+
+  @Override
+  public ClassElement getConstructorType() {
+    return enclosingClass;
+  }
+
+  @Override
+  public boolean isInterface() {
+    return false;
+  }
+
+  @Override
+  public Iterable<Element> getMembers() {
+    return Collections.emptyList();
+  }
+
+  @Override
+  public Element lookupLocalElement(String name) {
+    return null;
+  }
+}