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

runtime/vm/flow_graph_compiler_x64.cc

Index: runtime/vm/flow_graph_compiler_x64.cc
===================================================================
--- runtime/vm/flow_graph_compiler_x64.cc	(revision 29604)
+++ runtime/vm/flow_graph_compiler_x64.cc	(working copy)
@@ -670,22 +670,13 @@
 
   // 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.