Start using Dart_PropagateError in the runtime/bin directory.

runtime/bin/process.cc

 // Copyright (c) 2012, 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 "bin/dartutils.h"
 #include "bin/process.h"
 
 #include "include/dart_api.h"
 
 void FUNCTION_NAME(Process_Start)(Dart_NativeArguments args) {
@@ skipping 16 matching lines @@
     Dart_ExitScope();
     return;
   }
   const char* path = DartUtils::GetStringValue(path_handle);
   Dart_Handle arguments = Dart_GetNativeArgument(args, 2);
   // The arguments are copied into a non-extensible array in the
   // dart code so this should not fail.
   ASSERT(Dart_IsList(arguments));
   intptr_t length = 0;
   Dart_Handle result = Dart_ListLength(arguments, &length);
-  ASSERT(!Dart_IsError(result));
+  if (Dart_IsError(result)) {
+    Dart_PropagateError(result);
+  }
   char** string_args = new char*[length];
   for (int i = 0; i < length; i++) {
     Dart_Handle arg = Dart_ListGetAt(arguments, i);
-    ASSERT(!Dart_IsError(arg));
+    if (Dart_IsError(arg)) {
+      delete[] string_args;
+      Dart_PropagateError(arg);
+    }
     // The Dart code verifies that the arguments implement the String
     // interface. However, only builtin Strings are handled by
     // GetStringValue.
     if (!Dart_IsString(arg)) {
       DartUtils::SetIntegerField(status_handle, "_errorCode", 0);
       DartUtils::SetStringField(
           status_handle, "_errorMessage", "Arguments must be builtin strings");
       delete[] string_args;
       Dart_SetReturnValue(args, Dart_NewBoolean(false));
       Dart_ExitScope();
@@ skipping 55 matching lines @@
 }
 
 
 void FUNCTION_NAME(Process_Kill)(Dart_NativeArguments args) {
   Dart_EnterScope();
   intptr_t pid = DartUtils::GetIntegerValue(Dart_GetNativeArgument(args, 1));
   bool success = Process::Kill(pid);
   Dart_SetReturnValue(args, Dart_NewBoolean(success));
   Dart_ExitScope();
 }