Allow for instance checking of methods and function aliases.

compiler/java/com/google/dart/compiler/backend/js/DollarMangler.java

Index: compiler/java/com/google/dart/compiler/backend/js/DollarMangler.java
diff --git a/compiler/java/com/google/dart/compiler/backend/js/DollarMangler.java b/compiler/java/com/google/dart/compiler/backend/js/DollarMangler.java
index 08d55ace75430cb105aa578b47028ebccb653ae0..e10131f73c92f96d9c266f856170ff9abb701fff 100644
--- a/compiler/java/com/google/dart/compiler/backend/js/DollarMangler.java
+++ b/compiler/java/com/google/dart/compiler/backend/js/DollarMangler.java
@@ -44,6 +44,7 @@ public class DollarMangler implements DartMangler {
   private static final String FIELD_SUFFIX = "$field";
   private static final String METHOD_SUFFIX = "$member";
   private static final String NAMED_SUFFIX = "$named";
+  private static final String RTT_LOOKUP_SUFFIX = "$lookupRTT";
   private static final String CONSTRUCTOR_SUFFIX = "$Constructor";
   private static final String FACTORY_SUFFIX = "$Factory";
   private static final String INITIALIZER_SUFFIX = "$Initializer";
@@ -328,6 +329,24 @@ public class DollarMangler implements DartMangler {
   }
 
   @Override
+  public String mangleLookupMethod(MethodElement method, LibraryElement currentLibrary) {
+    // There can be no named shims for operators, getters, or setters.
+    String methodName = method.getName();
+    methodName = attachSuffix(methodName, RTT_LOOKUP_SUFFIX, currentLibrary);
+
+    String prefix = "";
+    if (ElementKind.of(method.getEnclosingElement()).equals(ElementKind.LIBRARY)) {
+      prefix = mangleLibraryName((LibraryElement) method.getEnclosingElement());
+    }
+    return prefix + methodName;
+  }
+
+  @Override
+  public String mangleLookupMethod(String methodName, LibraryElement currentLibrary) {
+    return attachSuffix(methodName, RTT_LOOKUP_SUFFIX, currentLibrary);
+  }
+
+  @Override
   public String mangleEntryPoint(MethodElement method, LibraryElement library) {
     Element holder = method.getEnclosingElement();
     switch (ElementKind.of(holder)) {