Deal with unhandled exceptions the same way in all Dart api functions.

runtime/vm/object.h

Index: runtime/vm/object.h
===================================================================
--- runtime/vm/object.h	(revision 1469)
+++ runtime/vm/object.h	(working copy)
@@ -139,7 +139,7 @@
     kExceptionHandlersClass,
     kContextClass,
     kContextScopeClass,
-    kApiFailureClass,
+    kApiErrorClass,
     kMaxId,
     kInvalidIndex = -1,
   };
@@ -239,7 +239,7 @@
   }
   static RawClass* context_class() { return context_class_; }
   static RawClass* context_scope_class() { return context_scope_class_; }
-  static RawClass* api_failure_class() { return api_failure_class_; }
+  static RawClass* api_error_class() { return api_error_class_; }
 
   static int GetSingletonClassIndex(const RawClass* raw_class);
   static RawClass* GetSingletonClass(int index);
@@ -332,7 +332,7 @@
   static RawClass* exception_handlers_class_;  // Class of ExceptionHandlers.
   static RawClass* context_class_;  // Class of the Context vm object.
   static RawClass* context_scope_class_;  // Class of ContextScope vm object.
-  static RawClass* api_failure_class_;  // Class of ApiFailure.
+  static RawClass* api_error_class_;  // Class of ApiError.
 
   friend class Class;
   friend class SnapshotReader;
@@ -2062,24 +2062,27 @@
 };
 
 
-class ApiFailure : public Object {
+class ApiError : public Object {
  public:
-  RawString* message() const { return raw_ptr()->message_; }
-  static intptr_t message_offset() {
-    return OFFSET_OF(RawApiFailure, message_);
+  RawObject* data() const { return raw_ptr()->data_; }
+  static intptr_t data_offset() {
+    return OFFSET_OF(RawApiError, data_);
   }
 
   static intptr_t InstanceSize() {
-    return RoundedAllocationSize(sizeof(RawApiFailure));
+    return RoundedAllocationSize(sizeof(RawApiError));
   }
 
-  static RawApiFailure* New(const String& message,
-                            Heap::Space space = Heap::kNew);
+  static RawApiError* New(const String& message,
+                          Heap::Space space = Heap::kNew);
 
+  static RawApiError* New(const UnhandledException& exception,
+                          Heap::Space space = Heap::kNew);
+
  private:
-  void set_message(const String& message) const;
+  void set_data(const Object& data) const;
 
-  HEAP_OBJECT_IMPLEMENTATION(ApiFailure, Object);
+  HEAP_OBJECT_IMPLEMENTATION(ApiError, Object);
   friend class Class;
 };