Remove support for interface in dart2js.

sdk/lib/_internal/compiler/implementation/warnings.dart

Index: sdk/lib/_internal/compiler/implementation/warnings.dart
diff --git a/sdk/lib/_internal/compiler/implementation/warnings.dart b/sdk/lib/_internal/compiler/implementation/warnings.dart
index 014415d8168f8c1c15705ed548776cd15433895e..00cdcce8bf6e2ce2fdcfc46441d26c30af6ab5a9 100644
--- a/sdk/lib/_internal/compiler/implementation/warnings.dart
+++ b/sdk/lib/_internal/compiler/implementation/warnings.dart
@@ -48,6 +48,10 @@ class MessageKind {
       'cannot resolve constructor #{constructorName}');
   static const CANNOT_RESOLVE_CONSTRUCTOR_FOR_IMPLICIT = const MessageKind(
       'cannot resolve constructor #{constructorName} for implicit super call');
+  static const INVALID_UNNAMED_CONSTRUCTOR_NAME = const MessageKind(
+      'Error: Unnamed constructor name must be #{name}.');
+  static const INVALID_CONSTRUCTOR_NAME = const MessageKind(
+      'Error: Constructor name must start with #{name}.');
   static const CANNOT_RESOLVE_TYPE = const MessageKind(
       'cannot resolve type #{typeName}');
   static const DUPLICATE_DEFINITION = const MessageKind(
@@ -64,8 +68,6 @@ class MessageKind {
       "'Object' does not have a superclass");
   static const CANNOT_FIND_CONSTRUCTOR = const MessageKind(
       'cannot find constructor #{constructorName}');
-  static const CANNOT_FIND_CONSTRUCTOR2 = const MessageKind(
-      'cannot find constructor #{constructorName} in #{className}');
   static const CYCLIC_CLASS_HIERARCHY = const MessageKind(
       '#{className} creates a cycle in the class hierarchy');
   static const INVALID_RECEIVER_IN_INITIALIZER = const MessageKind(
@@ -178,9 +180,6 @@ class MessageKind {
   static const NO_SUCH_LIBRARY_MEMBER = const MessageKind(
       '#{libraryName} has no member named #{memberName}');
 
-  static const CANNOT_INSTANTIATE_INTERFACE = const MessageKind(
-      "cannot instantiate interface '#{interfaceName}'");
-
   static const CANNOT_INSTANTIATE_TYPEDEF = const MessageKind(
       "cannot instantiate typedef '#{typedefName}'");