Implement type cast in the VM.

runtime/vm/exceptions.cc

 // 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.
 
 #include "vm/exceptions.h"
 
 #include "vm/cpu.h"
 #include "vm/dart_entry.h"
 #include "vm/debugger.h"
 #include "vm/flags.h"
@@ skipping 164 matching lines @@
   SetField(instance, cls, "column", Smi::Handle(Smi::New(column)));
 }
 
 
 // Allocate, initialize, and throw a TypeError.
 void Exceptions::CreateAndThrowTypeError(intptr_t location,
                                          const String& src_type_name,
                                          const String& dst_type_name,
                                          const String& dst_name,
                                          const String& malformed_error) {
-  // Allocate a new instance of TypeError.
-  const Instance& type_error = Instance::Handle(NewInstance("TypeError"));
+  // Allocate a new instance of TypeError or CastException.
+  Instance& type_error = Instance::Handle();
+  Class& cls = Class::Handle();
+  if (dst_name.Equals("type cast")) {
+    type_error = NewInstance("CastException");
+    cls = type_error.clazz();
+    cls = cls.SuperClass();
+  } else {
+    type_error = NewInstance("TypeError");
+    cls = type_error.clazz();
+  }
 
   // Initialize 'url', 'line', and 'column' fields.
   DartFrameIterator iterator;
   const Script& script = Script::Handle(GetCallerScript(&iterator));
-  const Class& cls = Class::Handle(type_error.clazz());
   // Location fields are defined in AssertionError, the superclass of TypeError.
   const Class& assertion_error_class = Class::Handle(cls.SuperClass());
   SetLocationFields(type_error, assertion_error_class, script, location);
 
   // Initialize field 'failedAssertion' in AssertionError superclass.
   // Printing the src_obj value would be possible, but ToString() is expensive
   // and not meaningful for all classes, so we just print '$expr instanceof...'.
   // Users should look at TypeError.ToString(), which contains more useful
   // information than AssertionError.failedAssertion.
   String& failed_assertion = String::Handle(String::New("$expr instanceof "));
@@ skipping 157 matching lines @@
     case kIsolateSpawn:
       library = Library::IsolateLibrary();
       class_name = String::NewSymbol("IsolateSpawnException");
       break;
   }
 
   return DartLibraryCalls::ExceptionCreate(library, class_name, arguments);
 }
 
 }  // namespace dart