Update Dart dependency to include fixes in x64 Dart precompilation

DEPS

@@ -25,7 +25,7 @@ vars = {
 
   # Note: When updating the Dart revision, ensure that all entries that are
   # dependencies of dart are also updated
-  'dart_revision': '6fd2fba704bb41b14b5819522c4282dd4659e08c',
+  'dart_revision': '29a44c7b4c592616c00bba58157ebcb0c80ff016',
   'dart_observatory_packages_revision': '5c199c5954146747f75ed127871207718dc87786',
   'dart_root_certificates_revision': 'c3a41df63afacec62fcb8135196177e35fe72f71',
 

sky/engine/core/script/dart_init.cc

@@ -86,10 +86,6 @@ static const char* kDartCheckedModeArgs[] = {
     "--error_on_bad_override",
 };
 
-void UnhandledExceptionCallback(Dart_Handle error) {
-  LOG(ERROR) << Dart_GetError(error);
-}
-
 void IsolateShutdownCallback(void* callback_data) {
   // TODO(dart)
 }
@@ -301,7 +297,7 @@ void InitDartVM() {
                           PrecompiledInstructionsSymbolIfPresent(),
                           IsolateCreateCallback,
                           nullptr,  // Isolate interrupt callback.
-                          UnhandledExceptionCallback, IsolateShutdownCallback,
+                          nullptr, IsolateShutdownCallback,
                           // File IO callbacks.
                           nullptr, nullptr, nullptr, nullptr,
                           // Entroy source