Rename class AssertError to AssertionError in the VM (fix issue 119).

runtime/lib/error.dart

 // 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.
 // Errors are created and thrown by DartVM only.
 // Changes here should also be reflected in corelib/error.dart as well
 
-class AssertError {
-  factory AssertError._uninstantiable() {
+class AssertionError {
+  factory AssertionError._uninstantiable() {
     throw const UnsupportedOperationException(
-        "AssertError can only be allocated by the VM");
+        "AssertionError can only be allocated by the VM");
   }
   static throwNew(int assertionStart, int assertionEnd)
-      native "AssertError_throwNew";
+      native "AssertionError_throwNew";
   String toString() {
     return "Failed assertion: '$failedAssertion' is not true " +
         "in $url at line $line, column $column.";
   }
   final String failedAssertion;
   final String url;
   final int line;
   final int column;
 }
 
-class TypeError extends AssertError {
+class TypeError extends AssertionError {
   factory TypeError._uninstantiable() {
     throw const UnsupportedOperationException(
         "TypeError can only be allocated by the VM");
   }
   String toString() {
     return "Failed type check: type $srcType is not assignable to type " +
         "$dstType of $dstName in $url at line " +
         "$line, column $column.";
   }
   final String srcType;
@@ skipping 12 matching lines @@
   }
   final String url;
   final int line;
 }
 
 class InternalError {
   const InternalError(this._msg);
   String toString() => "InternalError: '${_msg}'";
   final String _msg;
 }