Start using Dart_PropagateError in the runtime/bin directory.

runtime/bin/dartutils.h

Index: runtime/bin/dartutils.h
===================================================================
--- runtime/bin/dartutils.h	(revision 5191)
+++ runtime/bin/dartutils.h	(working copy)
@@ -56,6 +56,10 @@
 
 class DartUtils {
  public:
+  // The following Get/Set functions can call Dart_PropagateError(),
+  // which will never return.  If you have memory to deallocate or
+  // other C++ level cleanup pending, it is not approprate to call
+  // these functions.

[Søren Gjesse, 2012/03/08 21:18:46]

I can see how Dart_PropagateError makes it simpler to handle errors. However
this comment states why it is also error prone. This will lead to difficult to
find errors, so I am not sure I like it - of cause it is better than the ASSERTS
it is replacing.

Could it be an idea to have some kind of propagate scope to set up

{
  PropagateErrorScope s;
  // Call functions which use Dart_PropagateError
  ...
}

This will only be a marker at the call site that calls might never return.

Of cause all the functions below here should then check for this scope being
entered.

Not sure this realy helps though. 

[turnidge, 2012/03/08 22:19:26]

From offline discussion.

I will change the api to DartUtils to be less error prone in a follow-up CL. 
For the time being, I will leave the ASSERTs inside of DartUtils.

   static int64_t GetIntegerValue(Dart_Handle value_obj);
   static const char* GetStringValue(Dart_Handle str_obj);
   static bool GetBooleanValue(Dart_Handle bool_obj);
@@ -67,6 +71,7 @@
   static void SetStringField(Dart_Handle handle,
                              const char* name,
                              const char* val);
+
   static bool IsDartSchemeURL(const char* url_name);
   static bool IsDartExtensionSchemeURL(const char* url_name);
   static bool IsDartIOLibURL(const char* url_name);