| Index: sdk/lib/core/errors.dart | 
| diff --git a/sdk/lib/core/errors.dart b/sdk/lib/core/errors.dart | 
| index 2425189a868a9c87d2894f5555b36b06573d7e46..03b2798cfb7311c5e7e24e93e44ddbb19ec7281d 100644 | 
| --- a/sdk/lib/core/errors.dart | 
| +++ b/sdk/lib/core/errors.dart | 
| @@ -44,9 +44,8 @@ class ArgumentError implements Error { | 
| /** | 
| * Exception thrown because of an index outside of the valid range. | 
| * | 
| - * Temporarily implements [IndexOutOfRangeException] for backwards compatiblity. | 
| */ | 
| -class RangeError extends ArgumentError implements IndexOutOfRangeException { | 
| +class RangeError extends ArgumentError { | 
| // TODO(lrn): This constructor should be called only with string values. | 
| // It currently isn't in all cases. | 
| /** | 
| @@ -54,7 +53,7 @@ class RangeError extends ArgumentError implements IndexOutOfRangeException { | 
| * | 
| * Temporarily made const for backwards compatibilty. | 
| */ | 
| -  const RangeError(var message) : super(message); | 
| +  RangeError(var message) : super(message); | 
|  | 
| /** Create a new [RangeError] with a message for the given [value]. */ | 
| RangeError.value(num value) : super("value $value"); | 
| @@ -62,26 +61,6 @@ class RangeError extends ArgumentError implements IndexOutOfRangeException { | 
| String toString() => "RangeError: $message"; | 
| } | 
|  | 
| -/** | 
| - * Temporary backwards compatibilty class. | 
| - * | 
| - * This class allows code throwing the old [IndexOutOfRangeException] to | 
| - * work until they change to the new [RangeError] name. | 
| - * Constructor of [RangeError] is const only to support this interface. | 
| - */ | 
| -interface IndexOutOfRangeException extends Exception default RangeError { | 
| -  const IndexOutOfRangeException(var message); | 
| -} | 
| - | 
| - | 
| -/** | 
| - * Temporary backwards compatibility class. | 
| - * | 
| - * Removed when users have had time to change to using [ArgumentError]. | 
| - */ | 
| -class IllegalArgumentException extends ArgumentError { | 
| -  const IllegalArgumentException([argument = ""]) : super(argument); | 
| -} | 
|  | 
| /** | 
| * Error thrown when control reaches the end of a switch case. | 
| @@ -95,6 +74,7 @@ class FallThroughError implements Error { | 
| const FallThroughError(); | 
| } | 
|  | 
| + | 
| class AbstractClassInstantiationError implements Error { | 
| final String _className; | 
| const AbstractClassInstantiationError(String this._className); | 
| @@ -219,25 +199,16 @@ class UnsupportedError implements Error { | 
| * If a class is not intending to implement the feature, it should throw | 
| * an [UnsupportedError] instead. This error is only intended for | 
| * use during development. | 
| - * | 
| - * This class temporarily implements [Exception] for backwards compatibility. | 
| - * The constructor is temporarily const to support [NotImplementedException]. | 
| */ | 
| -class UnimplementedError implements UnsupportedError, NotImplementedException { | 
| +class UnimplementedError implements UnsupportedError { | 
| final String message; | 
| -  const UnimplementedError([String this.message]); | 
| +  UnimplementedError([String this.message]); | 
| String toString() => (this.message != null | 
| ? "UnimplementedError: $message" | 
| : "UnimplementedError"); | 
| } | 
|  | 
|  | 
| -/** Temporary class added for backwards compatibility. Will be removed. */ | 
| -interface NotImplementedException extends Exception default UnimplementedError { | 
| -  const NotImplementedException([String message]); | 
| -} | 
| - | 
| - | 
| /** | 
| * The operation was not allowed by the current state of the object. | 
| * | 
|  |