Implement latest spec changes regarding malformed types (see issue 14006):

runtime/vm/flow_graph_compiler_x64.cc

 // Copyright (c) 2013, 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/globals.h"  // Needed here to get TARGET_ARCH_X64.
 #if defined(TARGET_ARCH_X64)
 
 #include "vm/flow_graph_compiler.h"
 
 #include "vm/ast_printer.h"
@@ skipping 652 matching lines @@
 
   if (!FLAG_eliminate_type_checks || dst_type.IsMalformed()) {
     // If type checks are not eliminated during the graph building then
     // a transition sentinel can be seen here.
     __ CompareObject(RAX, Object::transition_sentinel(), PP);
     __ j(EQUAL, &is_assignable);
   }
 
   // Generate throw new TypeError() if the type is malformed or malbounded.
   if (dst_type.IsMalformed() || dst_type.IsMalbounded()) {
-    Error& error = Error::Handle();
-    if (dst_type.IsMalformed()) {
-      error = dst_type.malformed_error();
-    } else {
-      const bool is_malbounded = dst_type.IsMalboundedWithError(&error);
-      ASSERT(is_malbounded);
-    }
-    const String& error_message = String::ZoneHandle(
-        Symbols::New(error.ToErrorCString()));
     __ PushObject(Object::ZoneHandle(), PP);  // Make room for the result.
     __ pushq(RAX);  // Push the source object.
     __ PushObject(dst_name, PP);  // Push the name of the destination.
-    __ PushObject(error_message, PP);
+    __ PushObject(dst_type, PP);  // Push the type of the destination.
     GenerateRuntimeCall(token_pos,
                         deopt_id,
-                        kMalformedTypeErrorRuntimeEntry,
+                        kBadTypeErrorRuntimeEntry,
                         3,
                         locs);
     // We should never return here.
     __ int3();
 
     __ Bind(&is_assignable);  // For a null object.
     __ popq(RDX);  // Remove pushed instantiator type arguments.
     __ popq(RCX);  // Remove pushed instantiator.
     return;
   }
@@ skipping 1248 matching lines @@
   __ movups(reg, Address(RSP, 0));
   __ AddImmediate(RSP, Immediate(kFpuRegisterSize), PP);
 }
 
 
 #undef __
 
 }  // namespace dart
 
 #endif  // defined TARGET_ARCH_X64