Throw TypeError instead of CastError for type coercions.

tool/input_sdk/private/ddc_runtime/operations.dart

 // Copyright (c) 2015, 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.
 
 /// This library defines runtime operations on objects used by the code
 /// generator.
 part of dart._runtime;
 
 _canonicalFieldName(obj, name, args, displayName) => JS('', '''(() => {
   $name = $canonicalMember($obj, $name);
@@ skipping 228 matching lines @@
   // If strongInstanceOf returns null, convert to false here.
   if (($obj == null) || $strongInstanceOf($obj, $type, true)) return true;
   return false;
 })()''');
 
 @JSExportName('is')
 instanceOf(obj, type) => JS('', '''(() => {
   let result = $strongInstanceOf($obj, $type);
   if (result !== null) return result;
   let actual = $getReifiedType($obj);
-  $throwStrongModeError('Strong mode is check failure: ' +
+  $throwStrongModeError('Strong mode is-check failure: ' +
     $typeName(actual) + ' does not soundly subtype ' +
     $typeName($type));
 })()''');
 
 @JSExportName('as')
 cast(obj, type) {
   if (JS('bool', '# == #', type, dynamic) || obj == null) return obj;
   bool result = strongInstanceOf(obj, type, true);
   if (JS('bool', '#', result)) return obj;
   _throwCastError(obj, type, result);
 }
 
+check(obj, type) {
+  if (JS('bool', '# == #', type, dynamic) || obj == null) return obj;
+  bool result = strongInstanceOf(obj, type, true);
+  if (JS('bool', '#', result)) return obj;
+  _throwTypeError(obj, type, result);
+}
+
 bool test(obj) {
   if (obj is bool) return obj;
   return booleanConversionFailed(obj);
 }
 
 bool booleanConversionFailed(obj) {
   if (obj == null) {
     throw new BooleanConversionAssertionError();
   }
   var actual = getReifiedType(obj);
   var expected = JS('', '#', bool);
   throw new TypeErrorImplementation.fromMessage(
       "type '${typeName(actual)}' is not a subtype of "
       "type '${typeName(expected)}' in boolean expression");
 }
 
 void _throwCastError(obj, type, bool result) {
   var actual = getReifiedType(obj);
-  if (result == false) throwCastError(actual, type);
+  if (result == false) throwCastError(obj, actual, type);
 
-  throwStrongModeError('Strong mode cast failure from ' +
-      typeName(actual) + ' to ' + typeName(type));
+  throwStrongModeCastError(obj, actual, type);
+}
+
+void _throwTypeError(obj, type, bool result) {
+  var actual = getReifiedType(obj);
+  if (result == false) throwTypeError(obj, actual, type);
+
+  throwStrongModeTypeError(obj, actual, type);
 }
 
 asInt(obj) {
   if (obj == null) return null;
 
   if (JS('bool', 'Math.floor(#) != #', obj, obj)) {
-    throwCastError(getReifiedType(obj), JS('', '#', int));
+    throwCastError(obj, getReifiedType(obj), JS('', '#', int));
   }
   return obj;
 }
 
 equals(x, y) => JS('', '''(() => {
   if ($x == null || $y == null) return $x == $y;
   let eq = $x['=='];
   return eq ? eq.call($x, $y) : $x === $y;
 })()''');
 
@@ skipping 286 matching lines @@
     constructor(dartIterator) {
       this.dartIterator = dartIterator;
     }
     next() {
       let i = this.dartIterator;
       let done = !i.moveNext();
       return { done: done, value: done ? void 0 : i.current };
     }
   }
 ''');